magnet separator dn315

food grade magnetic separators - magnattack global

food grade magnetic separators - magnattack global

In these difficult and uncertain times, food processing is one essential industry that must keep on goingand our support to you will continue. Although site visits may be restricted, our team is always able to assist you over the phone, email, or video conference with any metal contamination concerns or enquiries you may have. Please dont hesitate to contact your account managers directly or reach out to us here.

For our Australian customers, the government has introduced major economic stimulus packages to assist businesses during the COVID-19 crisis. Our technicians are available to discuss the Instant Asset Write-Off Scheme. Please note, all purchases must be delivered by June 30, 2020.

Magnattack Magnetic Separators are designed to be sanitary, robust, and versatile. With powerful RE80 Magnet Technology combined with 50 years of hands-on, focused experience in the food industry, our solutions can provide you with an unmatched level of foreign metal control required to protect your product, brand and equipment. Our solutions can be tailored to specifically suit your application. For custom designs or assistance with selecting the right magnetic separator, please contact a Magnattack technician here.

The majority of Magnattack equipment solutions are a direct result of issues experienced by clients with existing low-quality and inadequate magnet technology. The Magnattack research and development team was able to work with the clients to create a solution that met their individual requirements, and consequently the requirements of other food companies experiencing the same difficulties. Our solution-based equipment range has been designed to specifically address current requirements and meet food industry standards. Ongoing research is continuously conducted by our team this proactive approach ensures we are able to understand and address our customers needs to the highest level possible.

All applications are individually assessed before recommendations are made and equipment is made to suit. Magnattack equipment is predominantly manufactured with proprietary RE80 magnet circuit technology, which ensures magnet strength life and separation efficiency is maintained for many years. RE80 assures the proven, long-term magnet strength life of Magnattack equipment and is the guarantee that our equipment does not contain inferior lower cost rare earth magnets.

All Magnattack equipment is fully manufactured in Australia and not imported. Our US sales and support team in Minnesota USA is also available to help with any magnetic separation enquiries you may have.

magnet separator | henan deya machinery co., ltd

magnet separator | henan deya machinery co., ltd

Dry low-intensity magnetic separation is confined mainly to the concentration of coarse sands which are strongly magnetic, the process being known as cobbing, and often being carried out in drum separators. Below the 0.5 cm size range, dry separation tends to be replaced by wet methods, which produce much less dust loss and usually a cleaner product. Low-intensity wet separation is now widely used for purifying the magnetic medium in the dense medium separation process, as well as for the concentration of ferromagnetic sands. Read more

how magnetic separator works | henan deya machinery co., ltd

how magnetic separator works | henan deya machinery co., ltd

Dry low-intensity magnetic separation is confined mainly to the concentration of coarse sands which are strongly magnetic, the process being known as cobbing, and often being carried out in drum separators. Below the 0.5 cm size range, dry separation tends to be replaced by wet methods, which produce much less dust loss and usually a cleaner product. Low-intensity wet separation is now widely used for purifying the magnetic medium in the dense medium separation process, as well as for the concentration of ferromagnetic sands.

Drum separators are the most common machines in current use for cleaning the medium in DMS circuits and are widely used for concentrating finely ground iron ore. They consist essentially of a rotating non-magnetic drum (see attached figure 1 drum separator) containing three to six stationary magnets of alternating polarity, although the Permos separator uses many small magnet blocks, whose direction of magnetisation changes in small steps. This is said to generate a very even magnetic field, requiting less magnetic material. figure 1 drum separator Although initially drum separators employed electromagnets, permanent magnets are used in modern devices, utilising ceramic or rare earth magnetic alloys, which retain their intensity for an indefinite period. Separation is by the pick-up principle. Magnetic particles are lifted by the magnets and pinned to the drum and are conveyed out of the field, leaving the gangue in the tailings compartment. Water is introduced into the machine to provide a current which keeps the pulp in suspension. Field intensities of up to 0.7 T at the pole surfaces can be obtained in this type of separator. The drum separator shown in figure 1 is of the concurrent type, whereby the concentrate is carried forward by the drum and passes through a gap, where it is compressed and dewatered before leaving the separator. This design is most effective for producing an extremely clean magnetic concentrate from relatively coarse materials and is widely used in dense medium recovery systems. The separator shown in figure 2 is of the counter-rotation type, where the feed flows in the opposite direction to the rotation. This type is used in roughing operations, where occasional surges in feed must be handled, where magnetic material losses are to be held to a minimum, while an extremely clean concentrate is not required, and when high solids loading is encountered. figure 2 Counter-rotation drum separator Figure 3 shows a counter-current separator, where the tailings are forced to travel in the opposite direction to the drum rotation and are discharged into the tailings chute. This type of separator is designed for finishing operations on relatively fine material, of particle size less than about 250 m. Drum separators are widely used to treat low grade taconite ores, which contain 40-50% Fe, mainly as magnetite, but in some areas with hematite, finely disseminated in bands in hard siliceous rocks. Very fine grinding is necessary to free the iron minerals that produce a concentrate that requires pelletising before being fed to the blast furnaces. figure 3 Counter-current separator In a typical flowsheet the ore is ground progressively finer, the primary grind usually being undertaken autogenously, or by rod milling, followed by magnetic separation in drum separators. The magnetic concentrate is reground and again treated in drum separators. This concentrate may be further reground, followed by a third stage of magnetic separation. The tailings from each stage of magnetic separation are either rejected or, in some cases, treated by spiral or cone concentrators to recover hematite. The cross-belt separator (see attached figure 4) and disc separators once widely used in the mineral sands industry, particularly for recovering ilmenite from heavy mineral concentrates, are now considered obsolete. They are being replaced with rare earth roll magnetic separators and rare earth drum magnetic separators. figure 4 Cross-belt separator Rare earth roll separators use alternate magnetic and non-magnetic laminations. Feed is carried onto the magnetic roll by means of a thin belt as shown in Figure 4, hence there is no bouncing or scattering of particles as they enter the magnetic zone, and they all enter the magnetic zone with the same horizontal velocity. These factors contribute to achieving a sharp separation. Roll speed can be adjusted over a wide range, allowing the product quality to be dialled in. Dry rare earth drum separators provide a fan of separated particles which can often be seen as distinct streams (see attached figure 5). The fan can be separated into various grades of magnetic product and a nonmagnetic tailing. In some mineral sands applications, drum separators have been integrated with one or more rare earth rolls, arranged to treat the middlings particles from the drum as shown in Figure 5. figure 5 A laboratory dry rare earth drum separator Pictures of Drum Separators Pictures of drum separators produced by Henan Deya Machinery Co., Ltd. magnetic-separator_01magnetic-separator_11magnetic-separator_10magnetic-separator_09magnetic-separator_08magnetic-separator_07magnetic-separator_06magnetic-separator_05magnetic-separator_04magnetic-separator_03magnetic-separator_02

Although initially drum separators employed electromagnets, permanent magnets are used in modern devices, utilising ceramic or rare earth magnetic alloys, which retain their intensity for an indefinite period. Separation is by the pick-up principle. Magnetic particles are lifted by the magnets and pinned to the drum and are conveyed out of the field, leaving the gangue in the tailings compartment. Water is introduced into the machine to provide a current which keeps the pulp in suspension. Field intensities of up to 0.7 T at the pole surfaces can be obtained in this type of separator.

The drum separator shown in figure 1 is of the concurrent type, whereby the concentrate is carried forward by the drum and passes through a gap, where it is compressed and dewatered before leaving the separator. This design is most effective for producing an extremely clean magnetic concentrate from relatively coarse materials and is widely used in dense medium recovery systems.

The separator shown in figure 2 is of the counter-rotation type, where the feed flows in the opposite direction to the rotation. This type is used in roughing operations, where occasional surges in feed must be handled, where magnetic material losses are to be held to a minimum, while an extremely clean concentrate is not required, and when high solids loading is encountered. figure 2 Counter-rotation drum separator Figure 3 shows a counter-current separator, where the tailings are forced to travel in the opposite direction to the drum rotation and are discharged into the tailings chute. This type of separator is designed for finishing operations on relatively fine material, of particle size less than about 250 m. Drum separators are widely used to treat low grade taconite ores, which contain 40-50% Fe, mainly as magnetite, but in some areas with hematite, finely disseminated in bands in hard siliceous rocks. Very fine grinding is necessary to free the iron minerals that produce a concentrate that requires pelletising before being fed to the blast furnaces. figure 3 Counter-current separator In a typical flowsheet the ore is ground progressively finer, the primary grind usually being undertaken autogenously, or by rod milling, followed by magnetic separation in drum separators. The magnetic concentrate is reground and again treated in drum separators. This concentrate may be further reground, followed by a third stage of magnetic separation. The tailings from each stage of magnetic separation are either rejected or, in some cases, treated by spiral or cone concentrators to recover hematite. The cross-belt separator (see attached figure 4) and disc separators once widely used in the mineral sands industry, particularly for recovering ilmenite from heavy mineral concentrates, are now considered obsolete. They are being replaced with rare earth roll magnetic separators and rare earth drum magnetic separators. figure 4 Cross-belt separator Rare earth roll separators use alternate magnetic and non-magnetic laminations. Feed is carried onto the magnetic roll by means of a thin belt as shown in Figure 4, hence there is no bouncing or scattering of particles as they enter the magnetic zone, and they all enter the magnetic zone with the same horizontal velocity. These factors contribute to achieving a sharp separation. Roll speed can be adjusted over a wide range, allowing the product quality to be dialled in. Dry rare earth drum separators provide a fan of separated particles which can often be seen as distinct streams (see attached figure 5). The fan can be separated into various grades of magnetic product and a nonmagnetic tailing. In some mineral sands applications, drum separators have been integrated with one or more rare earth rolls, arranged to treat the middlings particles from the drum as shown in Figure 5. figure 5 A laboratory dry rare earth drum separator Pictures of Drum Separators Pictures of drum separators produced by Henan Deya Machinery Co., Ltd. magnetic-separator_01magnetic-separator_11magnetic-separator_10magnetic-separator_09magnetic-separator_08magnetic-separator_07magnetic-separator_06magnetic-separator_05magnetic-separator_04magnetic-separator_03magnetic-separator_02

Figure 3 shows a counter-current separator, where the tailings are forced to travel in the opposite direction to the drum rotation and are discharged into the tailings chute. This type of separator is designed for finishing operations on relatively fine material, of particle size less than about 250 m. Drum separators are widely used to treat low grade taconite ores, which contain 40-50% Fe, mainly as magnetite, but in some areas with hematite, finely disseminated in bands in hard siliceous rocks. Very fine grinding is necessary to free the iron minerals that produce a concentrate that requires pelletising before being fed to the blast furnaces. figure 3 Counter-current separator In a typical flowsheet the ore is ground progressively finer, the primary grind usually being undertaken autogenously, or by rod milling, followed by magnetic separation in drum separators. The magnetic concentrate is reground and again treated in drum separators. This concentrate may be further reground, followed by a third stage of magnetic separation. The tailings from each stage of magnetic separation are either rejected or, in some cases, treated by spiral or cone concentrators to recover hematite. The cross-belt separator (see attached figure 4) and disc separators once widely used in the mineral sands industry, particularly for recovering ilmenite from heavy mineral concentrates, are now considered obsolete. They are being replaced with rare earth roll magnetic separators and rare earth drum magnetic separators. figure 4 Cross-belt separator Rare earth roll separators use alternate magnetic and non-magnetic laminations. Feed is carried onto the magnetic roll by means of a thin belt as shown in Figure 4, hence there is no bouncing or scattering of particles as they enter the magnetic zone, and they all enter the magnetic zone with the same horizontal velocity. These factors contribute to achieving a sharp separation. Roll speed can be adjusted over a wide range, allowing the product quality to be dialled in. Dry rare earth drum separators provide a fan of separated particles which can often be seen as distinct streams (see attached figure 5). The fan can be separated into various grades of magnetic product and a nonmagnetic tailing. In some mineral sands applications, drum separators have been integrated with one or more rare earth rolls, arranged to treat the middlings particles from the drum as shown in Figure 5. figure 5 A laboratory dry rare earth drum separator Pictures of Drum Separators Pictures of drum separators produced by Henan Deya Machinery Co., Ltd. magnetic-separator_01magnetic-separator_11magnetic-separator_10magnetic-separator_09magnetic-separator_08magnetic-separator_07magnetic-separator_06magnetic-separator_05magnetic-separator_04magnetic-separator_03magnetic-separator_02

In a typical flowsheet the ore is ground progressively finer, the primary grind usually being undertaken autogenously, or by rod milling, followed by magnetic separation in drum separators. The magnetic concentrate is reground and again treated in drum separators. This concentrate may be further reground, followed by a third stage of magnetic separation. The tailings from each stage of magnetic separation are either rejected or, in some cases, treated by spiral or cone concentrators to recover hematite.

The cross-belt separator (see attached figure 4) and disc separators once widely used in the mineral sands industry, particularly for recovering ilmenite from heavy mineral concentrates, are now considered obsolete. They are being replaced with rare earth roll magnetic separators and rare earth drum magnetic separators. figure 4 Cross-belt separator Rare earth roll separators use alternate magnetic and non-magnetic laminations. Feed is carried onto the magnetic roll by means of a thin belt as shown in Figure 4, hence there is no bouncing or scattering of particles as they enter the magnetic zone, and they all enter the magnetic zone with the same horizontal velocity. These factors contribute to achieving a sharp separation. Roll speed can be adjusted over a wide range, allowing the product quality to be dialled in. Dry rare earth drum separators provide a fan of separated particles which can often be seen as distinct streams (see attached figure 5). The fan can be separated into various grades of magnetic product and a nonmagnetic tailing. In some mineral sands applications, drum separators have been integrated with one or more rare earth rolls, arranged to treat the middlings particles from the drum as shown in Figure 5. figure 5 A laboratory dry rare earth drum separator Pictures of Drum Separators Pictures of drum separators produced by Henan Deya Machinery Co., Ltd. magnetic-separator_01magnetic-separator_11magnetic-separator_10magnetic-separator_09magnetic-separator_08magnetic-separator_07magnetic-separator_06magnetic-separator_05magnetic-separator_04magnetic-separator_03magnetic-separator_02

Rare earth roll separators use alternate magnetic and non-magnetic laminations. Feed is carried onto the magnetic roll by means of a thin belt as shown in Figure 4, hence there is no bouncing or scattering of particles as they enter the magnetic zone, and they all enter the magnetic zone with the same horizontal velocity. These factors contribute to achieving a sharp separation. Roll speed can be adjusted over a wide range, allowing the product quality to be dialled in.

Dry rare earth drum separators provide a fan of separated particles which can often be seen as distinct streams (see attached figure 5). The fan can be separated into various grades of magnetic product and a nonmagnetic tailing. In some mineral sands applications, drum separators have been integrated with one or more rare earth rolls, arranged to treat the middlings particles from the drum as shown in Figure 5. figure 5 A laboratory dry rare earth drum separator Pictures of Drum Separators Pictures of drum separators produced by Henan Deya Machinery Co., Ltd. magnetic-separator_01magnetic-separator_11magnetic-separator_10magnetic-separator_09magnetic-separator_08magnetic-separator_07magnetic-separator_06magnetic-separator_05magnetic-separator_04magnetic-separator_03magnetic-separator_02

Pictures of drum separators produced by Henan Deya Machinery Co., Ltd. magnetic-separator_01magnetic-separator_11magnetic-separator_10magnetic-separator_09magnetic-separator_08magnetic-separator_07magnetic-separator_06magnetic-separator_05magnetic-separator_04magnetic-separator_03magnetic-separator_02

eriez magnetic separation

eriez magnetic separation

Eriez Permanent Magnetic Separators require no electric power. With proper care, they can last a lifetime with very little loss of magnetic field strength. Eriez permanent magnets are supplied for a wide range of applications including dry bulk materials, liquids or slurries and even high temperature applications. Select Eriez Permanent Magnetic Separators are available with the Xtreme RE7 Magnetic Circuit - the industry's strongest magnet!

Eriez Permanent Magnetic Separators require no electric power. With proper care, they can last a lifetime with very little loss of magnetic field strength. Eriez permanent magnets are supplied for a wide range of applications including dry bulk materials, liquids or slurries and even high temperature applications.

Electromagnetic Separators use wire coils and direct current to provide a magnetic field which can be used to separate ferrous material from non ferrous products. Electromagnetic separators offer greater flexibility and strength as well as different magnetic fields for specific applications.

dn315 polyethylene electrofusion coupler for water pipe

dn315 polyethylene electrofusion coupler for water pipe

PE SOCKET COUPLER DN315PE ELECTROFUSION FITTINGS SDR11 PE100 Electrofusion Fittings socket coupler applied for gas pipeline pressure reach 0.7Mpa, and water-supply pipeline pressure reach 1,6Mpa; PE Electrofusion FittingsGating Process: 1) Complete Procurement Management - Customized Service for your China procurement program; 2) Product Development - Professional support and management for the success of the project; 3) Quality Control - Quality assurance of your product manufactured in supplier logistic service; 4) Logistic Service - On time delivery; 5) Research and Reporting Services - Accurate and reliable information to make the right decision. PE Electrofusion FittingsAdvantage: 1.Light weight 2.Flexibility 3.Toughness 4.Chemically Inert 5.Resistance to Abrasion 6.Smooth surface 7.Environmental stress crack resistance 8.Corrosion resistance 9.Frost & rodent resistance 10.Hygienic safety 11.Easy & quick installation PE Electrofusion FittingsCertificate: 1) ISO system - Our products are of high quality. We ensure our production record is of integrity and traceability. 2) Patent Certificate - We constantly adapt and innovate to ensure our products stay successful in the growing market. 3) National Test Report - Our products are credible and competitive in globle market, meeting the ISO standard. 4) International certification - BSI certification with ISO4427/4437 as well as EN12201/1555. Product Name HDPE Electrofusion fittings Raw Material Borouge HE3490LS, Total XS50. Color Black and orange color Standard EN1555/EN12201/ISO4427/ISO4437/DIN8074 Pressure PN4(SDR33),PN6(SDR21),PN8(SDR17),PN10(SDR13.6),PN12.5(SDR13.6)PN16(SDR11) Certificate BSI in UK. Size 25-400mm Used Water,Gas and Energy mining develop. D mm D1 mm L mm L1 mm 315 388 305 150

PE Electrofusion FittingsGating Process: 1) Complete Procurement Management - Customized Service for your China procurement program; 2) Product Development - Professional support and management for the success of the project; 3) Quality Control - Quality assurance of your product manufactured in supplier logistic service; 4) Logistic Service - On time delivery; 5) Research and Reporting Services - Accurate and reliable information to make the right decision.

PE Electrofusion FittingsAdvantage: 1.Light weight 2.Flexibility 3.Toughness 4.Chemically Inert 5.Resistance to Abrasion 6.Smooth surface 7.Environmental stress crack resistance 8.Corrosion resistance 9.Frost & rodent resistance 10.Hygienic safety 11.Easy & quick installation

PE Electrofusion FittingsCertificate: 1) ISO system - Our products are of high quality. We ensure our production record is of integrity and traceability. 2) Patent Certificate - We constantly adapt and innovate to ensure our products stay successful in the growing market. 3) National Test Report - Our products are credible and competitive in globle market, meeting the ISO standard.

how to stop an explosion explosion decoupling systems - wolff group

how to stop an explosion explosion decoupling systems - wolff group

Where the production process involves combustible dusts, gases, vapours, or hybrid mixtures, an ignition can occur in a device or apparatus and, in consequence, an explosion. Since process plants constitute a kind of set of connected vessels, an explosion can spread to subsequent devices. This phenomenon is unacceptable from the point of view of explosive safety, but also from the point of view of the Polish and European law. But how to counteract it effectively? Learn the advantages and disadvantages of commonly applied protective systems.

As a rule, industrial devices do not function as autonomous entities. Most of them are interconnected with other process apparatus through different types of conveying systems, pipelines and channels. When flammable and explosive dusts, gases, vapours, or hybrid mixtures take part in the process, there is a serious risk of ignition and explosion. Effects of an explosion in an apparatus, i.e. flame and pressure, may be transmitted from that apparatus to the process installation connected to it. This can occur even when the device is protected against the effects of explosion by an explosion relief (venting) or suppression system of the HRD type.

Due to the high probability of explosion propagation between individual apparatuses of the process plant endangered with an explosion, the ATEX 137 and 95 Directives, as well as the Polish regulations and standards, impose on the plant owners the obligation to apply certified explosion decoupling systems (also called explosion isolation systems or fire barriers).

Several solutions that meet the requirements of the ATEX directive 95 are available on the market. However, they not always can be applied interchangeably and some of them are dedicated exclusively for specific applications and solutions. Below, the most important types of explosion decoupling systems are presented.

Back pressure flaps are an explosion isolation system dedicated to combustible dusts that are fan-extracted in vacuum dedusting units and/or central vacuum systems. The advantages of the solution are simple installation and a relatively low price.

Note, however, that due to the principle of operation, valves must be installed in a horizontal position and on a straight section of the pipeline (on the stretch between the flap and the device, no knees and other curvature can occur). Moreover, choosing a back pressure flap for a particular solution, the pressure drops generated by the flap should be taken into account. It is equally important that the diameter of the pipeline is the same size as the flap connections. One must also remember that a local change in the diameter of the pipeline, as aimed at adapting it to the dimensions of the back pressure flap, can have a negative impact on the proper functioning of the safeguard at the explosion time. In the event of an explosion, the flap must be most frequently returned to the manufacturer for inspection and re-admission to the operation.

Due to the principle of operation, internal elements of the flap valve are exposed to accelerated wear and in some cases, also to being coated with dust (moisture), which can lead to an abnormal operation of the system. For these reasons, back pressure flap s are subject to frequent inspections and surveys (inspections every 10-20 days on average; surveys on a quarterly basis and, where appropriate, even once a month). It should be remembered that the plant must be disabled during an inspection or survey.

It is very important that users of back pressure flaps are familiarised with the manufacturers documentation observe rigorously the recommendations contained therein. For example, in the Polish regulations, there is an outright requirement concerning surveys they should be carried out in accordance with the manufacturers documentation, but not less frequently than once a year.

A significant limitation for the use of back pressure flaps results also from the maximum values of the dust explosiveness parameters Kst and Pmax for which they can be used. In most cases flap valves with a diameter of DN315 can be used for dusts of classes St1 and St2. Flap valves with larger diameters can only be applied for the class St1 dust. Please also note that the reduced explosion pressure Pred in the dust extraction unit may not exceed the value of 0.5 or 0.6 bar, depending on the diameter of the back pressure flap.

Rotary valves are used as a dosing systems for feeding dry products and sluices to limit air flow in dust collection, central vacuum, and pneumatic conveying systems, etc. In addition, in the case when they are certified in accordance with the requirements of the ATEX 95 directive, they can be operated in the explosion risk zones and as the so called autonomous explosion decoupling systems.

Rotary valves with the ATEX certificate allowing for their operation in explosion risk areas, if properly selected, are not a source of ignition of a potentially explosive atmosphere. Neither can such type rotary valves be used as explosion decoupling systems.

Rotary valves with the ATEX certificate allowing for their operation both in explosion risk zones and as autonomous explosion decoupling systems (in the design resistant to a pressure and/or flame breakthrough).

When selecting rotary valves, the latter two types of the devices are often mistaken for each other. For instance, in requests for quotations and technical specifications, there frequently appear requirements that cellular wheel sluices must be ATEX-certified for a particular hazard zone e.g. 20 inside and 22 outside the device. However, that fact is ignored that the device will also work as autonomous explosion decoupling system. In consequence, incorrectly selected sluices are purchased and installed. Their subsequent replacement is frequently difficult and costly. It is because the manufacturer of the equipment purchased either or does not have rotary valves with the required certificate in the offer or the capacity of a properly certified sluice of the same size is lower than the required (due to the limitations included in the certificate for decoupling of explosions).

In some cases, application of an explosion decoupling system of the HRD type may prove to be a better solution than a replacement of the rotary valve. In most cases, this solution does not require an additional space for installation and the system can be installed directly on the existing channel or dump station (downstream the flap valve).

Just like any other anti-explosive system, rotary valves with the ATEX certification also require regular servicing. In this case, however, the producers most frequently indicate maximum periods between the subsequent overhauls in the technical documentation, with a reservation that an exact frequency depends on operating conditions and should be determined by the plant operator based on the operational experience.

In practice, this means that the services must be, in some cases, carried out several times a year or else, the ATEX certification will become invalid (certificate is valid for the maximum permitted gap between the rotor blades and the valve body).

The type HRD isolation system is the least invasive, and at the same time the easiest to use anti-explosive system intended for both newly constructed and existing plants. The basic elements of the system are: HRD cylinders with explosion suppressant powder, dynamic pressure sensors and/or flame sensors and a control unit.

The solution based on HRD cylinders can be used in most industrial installations, where we have to deal with dust, gases or hybrid mixtures, and with a closed-circuit transport (pipelines, canals, gravity, chain, scraper, or pneumatic transport systems, closed conveyors, etc.), as well as in all types of dedusting and central vacuum systems.

For the most advanced HRD systems on the market, restrictions on the use of the system are very limited and related to some specific and rare circumstances. We are talking here about the restriction resulting from the maximum limit values of the following coefficients: Kst (up to 500 bar x m/s), Pmax (12 bar), Pred (2 bar) and the presence of group IIC gases or metal dusts in the process. However, such situations are so exceptional that their market share can be counted in parts per thousand.

Both restrictions and requirements for installing HRD systems of individual producers are entered in ATEX certificates. To avoid any surprises, before choosing a system, the restrictions recorded in the certificates must analysed in detail and compare them with the design input or conditions prevailing in the operating system. This is especially important because the admissions and restrictions on the application of systems of individual manufacturers differ fundamentally.

Explosion isolation systems based on the HDR technology are also subject to mandatory inspections and their complexity and time requirements differ, depending on the manufacturer of the system. For the most advanced systems, inspections should be conducted once a year. There are also commercially available systems which require up to four inspection a year. So the high frequency of inspections (and the resulting costs) can quickly even out the apparent savings resulting from lower cost of the system.

In case of systems of some manufacturers, another problem may be the need to relieve the pressure in HRD cylinders or to lock them mechanically (it is easy to forget it before restarting) for each operation related to servicing of the process plant. Since any such operation requires a shutdown of the plant, prior to selection of the explosion insulation system, it should be established how frequent downtimes are acceptable to the user.

This solution is a rather rarely used because of its price, nonetheless, it has two unique features. The first one is the option to activate the valve by a signal from the decompression panel (explosion relief system) or an individual infrared sensor and the other, the possibility of reusing it after activation.

Since the main element of the valve member is a rubber sleeve which is clamped under pressure (min. 6 bar at the compressed air installation), its activation delay is significant as compared to e.g. the HRD system. As a result, the quench valve has to be installed in a considerable distance from the protected apparatus.

Due to its construction, the valve may only be used at pneumatic conveying lines or circular channels of dedusting systems. The respective admissible dust explosiveness parameters are as follows: Kst up to 200 barm/s, Pmax up to 10 bar and Pred up to 1 bar. Note, however, that the service life of the rubber contributions can be significantly reduced in the case of the products causing abrasion and with the increase in the flow rate of the product. Although the interval between inspections is one year, in the case of difficult media (abrasion), one should consider shortening of the interval to 2 or 3 months, since the probability that a worn-out valve will not close or will be too weak to stop the explosion is high in such a case.

A fast acting valve is the most resistant explosion decoupling system as adapted to most difficult situations. It works like typical knife gate valves, with the difference that their reaction time and the closure is extremely short. Furthermore, their resistance to explosion pressure in the case of small diameters is as high as 50 bar (for larger diameters up to 30 bar). These are the values that can probably be achieved only in the event of an explosion of hybrid mixtures. In standard applications, fast acting valves work with both dusts and gases as well as with hybrid mixtures. Just as HRD systems, they are activated by dynamic pressure sensors and/or flame sensors, and the whole system is managed by a dedicated control unit.

Fast acting valves can be operated a certified system of explosion decoupling at the plants which have been designed in such a way as to withstand the maximum explosion pressure (the so called structures resistant to 10 bar). The list of devices where this type of solution can be applied is virtually limited only by the diameter of the channel it should not exceed DN400. We are talking here about filtration units, cyclones, reactors, dryers, pressure vessels, silos, mills, etc. The only drawback of this solution is a very high price, especially for larger diameters. In exchange, however, we get a system which after an explosion, we can activate by ourselves, without interference of an external service. This is essential for the plants where the time for restoring the system efficiency is crucial.

VENTEX type valves are a passive explosion insulation system available in many sizes and versions. It is installed on channels of dedusting, central vacuum, positive and negative pressure transportation, drying or granulation systems. In most cases, these are structures resistant to maximum explosion pressures. The valve closes by the action of the explosion pressure wave moving in a pipeline. Due to the special design of the valve, in the form of a pear, the valve only slightly affects the mixture flowing through its interior. This solution is approved for use with flammable and explosive gases, dusts and hybrid mixtures. One must remember, however, that when dust are in the stream, their content must not exceed the limits specified in the documentation. This results from the valve structure, where the pear at the closure is pressed onto a special seal. Tolerances here are very small and amount to 0.1-0.15 mm. Too high dust content may cause overgrowing or abrasion of the valve seal, which may lead to malfunction.

Ventex valve is characterized by the widest range of versions. For example, it is available in a wide range of diameters (from DN100 to DN50), can be mounted horizontally or vertically, and provide single or bi-directional operation. Moreover, the available versions are made of stainless or normal steel and have an active closing mechanism.

The solution is simple to service and overhauls are usually performed not more frequently than once a year. Problems can arise, however, when there is too large amount of dust in the flow. A valve with a broken seal must be returned to the manufacturer for replacement and fitting of a new sealing. Since special equipment is needed, it is not possible to replace the seal on site. This involves about a month downtime of the plant or an installation of a reserve Ventex valve.

The basic objectives of the article were to draw attention to the need to apply explosion isolation systems and to identify the advantages and disadvantages of the different solutions available on the market. Although the material presented allows a broad look at the basic solutions, the selection the right system should be preceded by a study prepared by an engineer experienced in the field and by necessary calculations. Only such an approach ensures that an optimum solution is selected in terms of technology and economy, and, above all, in terms of process and explosive safety.

In order to facilitate the process of adapting production plants to the explosive safety requirements, GRUPA WOLFF has developed its own DSBW (Dedicated Explosive Safety System) programme. Its task boils down to analysing efficiently the critical components of the constructed or existing process plant and taking steps that will make it possible to eliminate them. DSBW is focused at the same time on three key areas:

Design office Fire protection solutions Engineering systems designs Fire safety Fire detection and alarm system Spark extinguishing systems Extinguishing systems Smoke removal and ventilation system Sound alarm systems Ex-Signal and escape sign luminaires Explosion safety Explosion protection Explosion suppression Explosion relief (venting) Explosion decoupling (isolation) Spark detection and extinguishing system Electrostatic earthing Flame arresters ATEX case studies and ATEX training ATEX training Explosion Safety Audit Determining Explosion Risk Zones Explosion Risk Assessment Explosion Protection Document CONTACT +48 12 2018 100 [email protected] ABOUT US Blog Express Przemysowy GENERAL TERMS AND CONDITIONS OF SALES Electrical Equipment Electrical connectivity EX ATEX Ex-Junction boxes and terminal enclosures ATEX Ex-Control units and control stations ATEX Ex-Safety and main current switches ATEX Ex-Control and distribution systems ATEX Ex-Cable glands ATEX Optical-acoustic signaling EX ATEX EX lighting EX-linear light fittings ATEX Ex LED lighting ATEX EX-Ceiling pendant light fittings and floodlights ATEX EX-Signal and escape sign luminaires ATEX Portable EX-hand lamps ATEX EX Heating Room heaters Fan heaters Line liquid heaters Process media heaters Cabinet and enclosure heaters EX Thermostats Industrial Equipment Screening machines Mills for powders Valves / gates / dampers Sampling of loose material Granulators, dryers, coolers Magnetic separators Transport equipment Bead mills / mixers / deaerators Sludge and suspensions dryers / flakers Liquid samplers Industrial fittings Bursting discs Safety valves Reducing valves Breather valves Flame arresters Modernisation / Installation / Service Industrial systems and equipment service Industrial automation Modernisation and installation of equipment and steel structures Systems relocation Electric works for the industry Offer ATEX Explosion Risk Assessment Explosion Hazard Zones Explosion Protection Document EPD ATEX training HAZOP studies safety analysis of process systems ATEX audits and expert opinions Definition WOLFF GROUP provides specialised engineering works for broad industrial applications. Our activities include: explosion and process safety, turn-key construction of industrial systems, production and supply of process equipment and instruments as well as transfer of new technologies. Over 25 years of operation we have been trusted by hundreds of companies thank you. Copyright 2014 - WOLFF GROUP. All rights reserved.

WOLFF GROUP provides specialised engineering works for broad industrial applications. Our activities include: explosion and process safety, turn-key construction of industrial systems, production and supply of process equipment and instruments as well as transfer of new technologies. Over 25 years of operation we have been trusted by hundreds of companies thank you.

Related Equipments