What is a Slide Gate Deflector Cone?

A slide gate deflector cone, referred to by Vortex as a Special Service Inlet (SSI), is an inexpensive deflector cone used in gravity flow applications that can extend the service life of your slide gate. The tapered deflector guides the material flow away from the gate’s inlet contact points, eliminating or reducing wear to the gate itself. The thin profile of the SSI (typically 3/16″ | 5mm) adds a minimal height to the gate’s profile, while the SSI extends inside the gate to just above the gate’s blade. The close proximity of the SSI to the blade ensures a cleaner seat and a tighter seal. For friable material, the SSI can be raised to help minimize the gate’s blade shearing of the material. The SSI can be manufactured for round, square, or rectangular gates, and can even be used as a transition from a round-to-square or square-to-round gate. The slide gate should be in the horizontal position for the inlet to work properly.

A Special Service Inlet is used for two primary purposes:

1. Prevent Abrasion to the Slide Gate-. This is done by directing material flow to the center of the gate, away from the sides and seal of the gate. The tapered ledge of the SSI serves as an umbrella where the abrasive material can repel against it. This shields the mouth of the gate from any wear from abrasive or coarse materials and the SSI becomes the wear piece. Even some fine powders can significantly wear the opening on a gate.

2. Prevent Material Packing – A Special Service Inlet also prevents material from being packed in the blade’s closure pocket or rammed into the end seal. Material on the leading edge of the blade falls away as the blade closely passes under the SSI. With no material, or a minimum of material, coming into contact with the gate’s seals, the seal life is extended significantly reducing the need for maintenance while maintaining a positive, dust tight seal.

 

The inexpensive cost of a Special Service Inlet can pay for itself many times over. Depending on the size of the gate, the SSI may be less than $100 or up to a few hundred dollars on very large gates. Gate cost may run from just a few hundred dollars to several thousand dollars, depending on size and construction. A SSI is essentially disposable and can be easily replaced multiple times over the life of a single gate. Also, the SSI helps to extend the life and performance of the seals. This helps you save time and lower maintenance costs by not having to take the gate out of service to replace the seals. In addition to, preventing a slide gate from becoming worn and leaking material also results in health and air quality benefits.

A Special Service Inlet can be on Vortex’s Orifice Gate, Roller Gate, Clear Action Gate, HDPV2, and Maintenance Gate. Some abrasive applications that Vortex has recommended a SSI for is handling ground coal, corn cobs, aqua feed, pebble lime, sand, slag and fly ash.

When considering using a SSI, you must remember that you are decreasing the circumference or area the material can flow. As a rule of thumb, a special service inlet will reduce the opening of the gate by about one gate size. If you have a 10″ roller gate, a square SSI with a .75″ | 20mm tapered lip will decrease the flow area by up to 1.5″ | 40mm. Relay the flow rates to your valve manufacturer who can help you determine the best size of valve and SSI for your gravity flow system.

By installing a Special Service Inlet on your gate valve, you can treat a SSI as a disposable piece at a relatively low cost compared to the cost of a new valve. This simple and inexpensive step will prolong the life of your slide gate.

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Minimizing Contamination: Food Friendly Loading Spouts

Vortex’s retractable loading spouts are used for loading dry bulk solid materials into vessels such as semi-tankers, open trucks, railcars, barges and ship holds, as well as open stockpiling.  In the grain industry, the transported materials are eventually ingested through food consumption which is a major concern for grain inspectors, elevator & mill operators and ultimately the consumer themselves.

During the 2014 tradeshow season, several attendees voiced some concerns about the design of our spout’s outer dust containment sleeve. They saw a likelihood for contamination to occur from metal fasteners inside the sleeve.

“Basically, they said the design was not food friendly.  I took these comments very seriously,” says Jon Jasinski, Vice President of Sales for Vortex’s Loading Solutions Division.  “I immediately challenged our engineers to develop a design that would combat these concerns.  Our group ultimately came up with some great ideas.”

One of the main concerns from the food industry was the loading spout industry’s standard method of utilizing aluminum and metal rings to support the outer dust containment sleeve; and more importantly how these inner and outer support rings are fastened to each other.   The industry standard is to drill and rivet the rings together, drill and bolt the rings together, or utilize self-tapping screws.  This method results in aluminum and/or metal shavings inside of the sleeve as it is being constructed.  Even though Vortex takes much effort in fully expanding the sleeve and cleaning it with compressed air, shavings can still get into the folds and ultimately fall out later when the spout is in operation.

Additionally, the food industry has a legitimate concern about the fasteners, i.e. rivets, bolts, and screws, which are used in the construction of the outer dust containment sleeve.  These fasteners can ultimately fail and then contaminate the product being transferred through the loading spout.  A flour producer, who spoke with Jasinski, said he lost eighteen rail cars of flour because they were contaminated with metal shavings and fasteners from a different manufacturer’s loading spout.

Spout-Old-Sleeve-Ring

Support rings are typically fastened together by rivets or screws that can deteriorate and contaminate the material load.

To combat this issue, Vortex changed the design of the outer dust containment sleeve by eliminating the need to mechanically fasten the inner and outer support rings together.  By utilizing low profile inner support rings in conjunction with custom extruded outer support rings that are assembled with a high performance clamping method, the need for mechanical fasteners have been totally eliminated.

By utilizing an exterior clamping method and newly designed inner and outer support rings, we were able to eliminate the need for mechanical fasteners and the potential for contaminating the load. This sleeve design is now standard on all Vortex loading spout orders regardless if it intended for a food grade application or not.

Spout-New-Sleeve-Ring

Vortex has redesigned the support rings to eliminate metal pieces on the interior of the spout.

The other major concern about the spout design came from a flour miller in Tennessee.  He suggested that Vortex take the lead and improve the method by which the way the inner material feed cones are cabled together.  He was involved in two (2) separate situations where the cable fasteners from a different manufacturer’s loading spout failed and contaminated loads of flour.

The industry standard is to fasten u-bolts to an “ear” that is welded to the metal stacking cone.  The nuts that hold the u-bolt in place can become loose over time and fall off.  Or even worse, the u-bolt itself can fail and in both instances, contaminate the product.

Spout-Old-Cable-Harness

The typical u-bolt and nut harness guides contain several pieces that could contaminate a load.

Wanting to improve our loading spout, our engineers redesigned the cable harness for the inner stacking cones. The new design incorporates a custom-machined steel peg which has a precision-drilled hole for the cable to pass through.  The cable is held in place by a set screw that is treated with Locktite®.  This new design feature is available on all food grade loading spouts.

Spout-New-Cable-Harness

Vortex redesigned the cable harness to reduce the risk of metal contamination.

Vortex will custom engineer your loading spout to meet any application, load rate or travel distance including corrosive or hazardous materials and extreme temperatures.

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Article publish in Processing Magazine >>

How to Select the Right Pneumatic Solenoid Valve

Slide gates and diverter valves that use pneumatic actuators (air cylinders) must be equipped with a properly matched pneumatic solenoid valve. The solenoid valve controls the flow of air pressure to the ports of the air cylinder to open or close a slide gate or switch a diverter. Solenoid valves are available in a number of different configurations based on their port size, flow factor and the application environment.

 

Single and Double Coil Solenoids: Which do I Need?

The general rule of thumb is that a single coil solenoid valve is specified for slide gates and a double coil solenoid valve is specified for diverter valves. When a single coil solenoid valve is connected to a slide gate, it is plumbed to open the slide gate when the solenoid valve is energized and close it when de-energized. The advantage of doing this is that the slide gate will close upon loss of electrical power. This is called “fail closed”.

With a double coil solenoid, a momentary electrical signal is required to reposition the blade. The blade stays in the last position until the opposite coil is energized with another signal. In case of power loss, the blade stays where it is. This is called “fail last position”, which maintains direction of the material flow.

 

Air Flow is Crucial in Delivering the Best Performance

Each solenoid is rated for flow in liters per minute or by a flow coefficient (Cv) or flow factor (Kv). The rated airflow of the solenoid valve must meet the bulk handling valve manufacturer’s requirements of air demand to the air cylinder. If purchasing solenoids locally, make sure the air flow and other ratings are a perfect match to the solenoid specified by the valve manufacturer. Using a lower flow solenoid valve will cause performance problems such as chattering and slow actuation of the blade.

Solenoid valves are available in a number of environmental ratings to match system requirements. In North America, UL listings and NEMA ratings must be considered for the solenoid valve coils to ensure that the solenoid valve is appropriate for the environment in which it will be used. In the European Union, ATEX must be considered for both the solenoid valve body and the coils when used in hazardous locations. In other locations throughout the world, internationally accepted ratings such as IECEx may apply or country specific ratings such as GOST-R may be required. Ingress Protection (IP), the degree of protection provided against the intrusion of dust and water, is an additional rating to consider.

 

Dealing with Power Failures – Fail-safe Devices

If a customer is planning to use an air cylinder to actuate a gate or diverter, another item may need to be considered. Electrical failure typically causes the loss of plant air. To ensure that enough compressed air is available to close a gate upon loss of plant air, customers might wish to consider an air fail-safe device. The air fail-safe is a reserve air tank that is outfitted with an air filter, pressure gauge, check valve, and fittings. The size of the tank depends on the volume requirements of the air cylinder used to power the gate. The check valve ensures there is enough air in the reserve tank to close the blade one time. The air tank may be mounted remotely up to 25 feet from the gate. An air fail-safe is an inexpensive insurance policy if shutting off the material flow is important during an unexpected loss of plant air.

*This article is based upon double acting air cylinders

 

Measuring Tube vs. Pipe For Bulk Solids

When designing a system or replacing a valve component, the question that commonly arises is “What’s the difference between a tube and a pipe?” Not a whole lot, but if you request a quote for a valve to connect to a 4″ tube when you really have a 4″ pipe, your valve is not going to fit.

Tube is used for powders, pellets, and granules, or in a dilute phase conveying system. The tube can be made from stainless steel, carbon steel, or aluminum. When you measure the outside diameter, otherwise identified by “O.D.”, you get the true measurement of the tube. A 4″ O.D. tube is exactly that, a tube that is 4 inches across the outside diameter.

Pipe, on the other hand, is used for abrasive materials or for dense phase conveying systems. Pipe can also be made from stainless steel, carbon steel, or aluminum. What makes it different from tube is how it is historically sized and the thickness of the pipe wall.

In the early 1900s, only three pipe thicknesses existed for the pipes that were casted in 2 pieces from wrought iron: STD (standard weight), which later became known as Schedule 40 pipe; XS (extra-strong), which later became known as Schedule 80 pipe; and XXS (double extra-strong), which later became known as Schedule 160 pipe. After WWII, pipes were being manufactured from stainless steel giving them a lighter weight and thinner wall thickness. Thus Schedule 5 pipe and Schedule 10 pipe were born.

The most common thicknesses in the dry bulk handling industry are Schedule 10, Schedule 40, and Schedule 80.

Pipe sizing is confusing because when you measure the outside diameter of a 4″pipe, it’s actually 4.5″. Every pipe is somewhat bigger than the labeled size until you reach 14″ and then the schedule pipe size is actually the outside diameter size. Originally, schedule pipe was labeled by the inside diameter size. But as the constructed material and wall thicknesses evolved, the inside diameter changed. The outside diameter stayed the same so it could mate with existing older pipe. Now, in order to have some form of consistency, pipe is ordered by the outside diameter measurement (example: 4″), which is a fixed value, then by schedule (example: Schedule 40), which determines the thickness of the wall.

If in doubt when you are ordering, measure the outside diameter of the tube/pipe and the inside diameter of the tube/pipe. Relay these measurements to your valve manufacturer who can help you determine if you have tube or pipe in your system. They can recommend the best size of valve for your system.

 

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Loading Spout vs. Loading Sock: What’s the Difference

Grain elevator sock. Drop-down sleeve. Spigot. Flexible bellow. Telescopic chute. Loading spout. There’s lots of words in different regions of the world to describe a long cylinder to load material from one place to another location via gravity. But what is the difference between a loading sock and a loading spout?

The Loading Sock

If your budget is tight, a loading sock is the perfect solution until you can upgrade your plant equipment with something a little more robust. Most loading socks are often made in a 6-8″|150-200mm diameter. The actual sock is a cylindrical tube of fabric sewn to be tapered much like that of a windsock, and can be made by a local tarp maker from canvas or polyurethane fabric. For support, the sock is then secured to a rigid steel piping. The loading sock is flexible and can easily hang down over the hatch of a semi-tank or railcar as well as the tops of open trucks and gondola type rail cars.

Material is fed into the top of the sock and then by gravity, falls into the transport vessel below. To guide the sock, you move it manually and in some cases, may have to physically hold it in place while the grain or powder falls to its destination. The free fall of material will most likely create fugitive dust when loading this way.

Once you have dumped the material, the sock is rolled up and secured to prevent additional material falling out, and to prevent contamination of the interior due to unwanted pests. The time and labor to seal the sock after each use can consume as much time and labor as loading the material into the railcar.

The Loading Spout

Installing a loading spout in your bulk handling system can contain the flow of material into a more confined area, thus reducing the radius of debris and dust. Unlike the one layer of a loading sock, a loading spout actually possesses three layers to help contain dust emissions:

1. Internal Stacking Cones – Layer one is a series of internal stacking cones that can be constructed from materials like AR steel or polymer.

Loading spout internal stacking cones

2. Fabric Outer Sleeve – Layer two is a fabric sleeve that encloses the cones keeping the dust inside the system.

Loading spout outer sleeve to contain dust

3. Neoprene Rubber Skirt – Layer three is a neoprene rubber skirt located at the bottom of the spout. Typically used in open loading applications, the skirt rests on top of the stockpile where the material flows.

Loading spout neoprene skirt for controlling dust during open loading

To fully control dust emissions during the loadout process, a fourth layer can be added. Loading spouts can be equipped with an in-line filtration system or integrated into an already existing dust filtration system. Using all four of these layers will drastically reduce dust emissions in comparison to using a sock.

Another benefit of a loading spout is the automation ability. A spout can be automated with a level-sensing probe to control the flow of material. When the spout is lowered into a railcar or stockpile, the slide gate at the top of the spout automatically opens. As the pile grows larger, the probe signals the spout to raises automatically to keep a consistent flow. Once the pile reaches a predetermined height, the automation closes the slide gate stopping the flow of material. This eliminates human error and wasted material costs due to overfilling.

Loading spouts can also be fitted with single and dual-axis positioners. This becomes useful when trucks, railcars, and vessels don’t always line up in the exact same place. When loading enclosed trucks or railcars, this process can be automated utilizing the hatch opening. The automated positioner can find the hatch and line up the spout accordingly.

The convenience of having a loading spout with automated controls, a dust filtration system, and the flexibility to move will come at a higher cost when compared to a loading sock. But if you consider safer working conditions, a reduction in plant cleaning costs, and a decrease in material waste, the ROI for a loading spout can easily outweigh the higher upfront costs in a short period of time.

 

Vortex Loading Spout Product Page

Why You Should Use Loading Spouts Article

 

Loading Spouts: Why You Should Be Using Them

A loading spout attached to the bottom of a silo or hopper, or located at the end of an air conveying system, is used for distributing dry bulk materials in open trucks, stockpiles, railcars, tank vehicles, barges and ships. It is used mostly in grain elevators, ship ports and cement plants conveying dry bulk material.

Here are three reasons why every operation which loads dry bulk material into open or closed vehicle containers needs retractable loading spouts as part of their process.

#1 – Capture Fugitive Dust: Health & Safety Issues

Clouds of debris and dust are formed when dry materials such as grain, coal, cement, and rock are loaded in bulk.  The airborne fugitive dust can cause employee health issues including chronic lung disease, eye sight problems and skin allergies.

Loading Spout fugitive dustEmployees are also prone to slips and falls when the fugitive dust accumulates on top of the vessels, elevated walkways, floors and ladder rungs. The dust accumulation problem in the grain industry can exacerbate because the dusting on top of building structural members, walkways, ducting, piping and equipment can cause dust explosions causing injuries, structural damage and even death.

Health and safety agencies can issue fines for job site injuries and citations if annual inspections are not up to par.  These costs can add drain a company financially.

Installing a  loading spout in your operation can contain the flow of material into a confined area reducing the radius of debris and dust.  With an additional aeration system added to the spout, more dust can be contained. An aeration system can be installed on the inside bottom of a storage container or mounted to follow a specific path inside the plant. Aeration systems include aerated conveyor systems, aerated bin bottoms, aerated trough systems and articulation arm positioners. All Vortex aeration systems are custom designed and manufactured to your individual project specification, so they can handle any material and desired flow rate.

#2 – Ensure Plant & Environmental Safety: Air Emission Issues

Spout-Article_regulationsAirborne fugitive dusting is a leading concern of environmental agencies resulting in large fines. In some cases, the government can shut down operations until improvements are made, which lead to lost shipping profits, customers, etc, for a company.

Having a loading spout with a blower and integral filter can send the fugitive dust to draft back through the sleeve of the loading spout, trapping material dust temporarily in the filter cartridges. An automatic onboard pulse system dislodges the dust and fine particles, reintroducing them back into the product feed. It continuously purges the filters to keep the equipment working optimally and free of dust build-up. This prolongs the life of the filter cartridges significantly.

#3 – Prevent Material Waste: Lost Profites & Clean-up Costs

Material lost due to fugitive dusting and spills over a year’s time can result in lost profits. Also, labor costs associated with having to clean up accumulated material over a year’s time can often times exceed the cost of a complete load-out system.

Spout-Article_wasteTo overcome these problems, the loading spout’s discharge cone should be designed to seat directly into railcar hatches and semi tankers to minimize fugitive dusting. Sensors attached to the inside of loading spouts automatically measure product levels. The sensors also provide a signal that automatically stops the flow of materials to prevent overfilling and/or plugging within the spout.

The hopper’s discharge flange is designed to directly connect to the inlet of the loading spout. A pre-wired handheld control pendant with push buttons is available as an option to allow the operator to manually control the positioner, which can also be controlled remotely from a central location.

A loading positioner can also help minimize spills when loading.  The positioner is used in with standard volume loading spouts to facilitate and speed up the loading of open or enclosed trucks and railcars at loadout stations. They allow for the fast and accurate single-axis or double-axis placement of the loading spout, which eliminates the need to reposition vehicles once they have entered the loading station and overestimating the location of the vessel opening.

Complimentary Components

Most often, loading spout systems will be used in conjunction with slide gates, diverter valves and spinloaders that control the material flow during the loadout process. Used at the bottom of a silo or hopper to shut off material flow, slide gates are placed right above dust collecting filter systems, loading spouts and positioners.

Vortex offers a complete line of versatile loading spout systems, gates and diverters for your loading process. We can also custom engineer any telescopic loading spout system to meet your most demanding loadout application requirements, including corrosive or hazardous materials, long distances, low and high temperatures, etc. Vortex fully assembles, factory tests and packages every loading spout system before shipping it to your facility to provide ease of installation and to ensure optimal performance once in use.

Vortex Warranty

Vortex’s loading spouts are unique for loading bulk materials into open and/or enclosed vessels because of their 4-cable lifting design providing maximum stability, compared to the standard 2- or 3-cable systems. The in-line drive system also incorporates special 3-piece CNC-machined pulleys that feature chamfered edges and precision cable grooves to significantly reduce cable wear and back lashing as the loading spout extends and retracts, especially during the misalignment of the hatch opening. Because the cables do not fray, cable failure is nearly eliminated and so is costly downtime for repairs.

The warranty covers any Vortex loading spout cable that breaks due to friction from the pulley.  The 3-piece CNC machined pulley features chamfered edges and precision cable grooves to significantly reduce cable wear and back lashing as the loading spout extends and retracts. Because the cables do not fray, cable failure is nearly eliminated and so is costly downtime for repairs.

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Rotary vs. Flapper vs. Blade Style Diverter Valves

Factors to consider when selecting a diverter valve:

Selecting a diverter valve for your pneumatic conveying system can be a tough job, especially when it comes to considering how many diverter valves are on the market. Yet a properly selected diverter valve can keep your operation running smoothly, cut maintenance costs, and improve your conveying system’s efficiency. After outlining factors you should consider to select a diverter valve for your system, this article provides descriptions of commonly used diverter valves, how they work, how they’re applied, and their pros and cons.

Before you can select a diverter valve for your pneumatic conveying system, you need to consider several factors: your application type, your conveying system type, your material characteristics, valve cost, and valve options.

Application type – Most diverter valves, also called two way diverter valves, convey material from one source to two destinations. In some applications, a two-way diverter valve is installed backward in the line to convey material from two sources to one destination. When used this way, it’s called a two-way converger valve. However, be aware that turning a conventional two-way diverter valve into a converger valve may require the manufacturer to make costly design modifications that will increase the valve’s purchase price. It may be more practical to select a valve specifically designed for converging.

If your system has more than two material sources or destinations, you need to consider how each diverter valve can be installed to meet your system’s design criteria, as well as, your budget. One way to meet these constraints is to install a diverter valve with more than two ports, called a multiport diverter valve.

Conveying system type – Your diverter valve choice will depend on whether your pneumatic conveying system is dilute- or dense-phase and operates under pressure or vacuum. A dilute-phase system can have a conveying line pressure up to 15 psig or vacuum pressure down to 30 inches mercury, while a dense-phase system can have a conveying line pressure up to 90 psig. Make sure the valve you select will operate well in your conveying phase and at your system pressure or vacuum.

You also need to consider your pneumatic conveying system’s pressure or vacuum capabilities and line diameter, as well as the expected pressure drop across the valve, to help determine the valve’s minimum and maximum size. This ensures that the valve will function properly and efficiently after it’s installed in your system. To help you narrow the field, many manufacturers pressure-rate each of their valves and provide a valve-sizing chart listing each valve’s specifications and limitations.

Material characteristics – Consider your material’s characteristics, such as particle size and abrasiveness, to choose a diverter valve that can handle them. Particles that are too large for the valve you select

can become jammed between the diverter’s internal components, preventing the valve from fully closing off the specified downstream conveying line or lines (the closed line or closed lines) to air and material flow. Particles that are too small for your valve can become packed between the internal components, binding the diverter, or the material can pass into the closed line.

Material that’s too abrasive for your valve’s design can erode the valve components, creating a gap for air and material to pass through into the closed line. Air passing through this gap will create a pressure drop across the system that affects the system’s capacity and material passing through to the closed line may contaminate your finished product.

To fix these problems, you must shut down the conveying system and remove the valve to either clean or replace its internal parts. This creates lengthy production downtime, increases maintenance and production costs, and reduces your system’s efficiency. To prevent these problems, identify your material characteristics and choose a valve that can handle them.

Cost – A diverter valve’s purchase price is only one of many costs you need to consider. Others include shipping, installation, and maintenance costs, material cross-contamination costs associated with internal valve leaks, and lost-production costs caused by maintenance downtime. You can discover these and other performance-related costs by asking for information from users who have installed a particular valve in an application similar to yours.

Options – Depending on your material characteristics, you can specify that a diverter valve and its components be constructed of cast aluminum, cast iron, stainless steel, or a specialty alloy. And depending on your pneumatic conveying system’s specifications and power availability, you can often specify that a valve be actuated manually, by air, or by an electrical motor. You can also specify a valve with an air-controlled solenoid and position indicating switches.

Now, keep these selection factors in mind as you explore the types of available diverter valves. The following information covers five common diverter valves: rotary-plug, rotary-blade, flapper, sliding-blade, and flexible-tube. Multiple-source, multiple destination diverter valve configurations are also discussed.

Download the full white paper to get breakdown comparison of rotary style, flapper style, blade style and flexible tube diverter valve for handling dry material.

What’s the Best Slide Gate or Diverter Valve for Handling Abrasives?

Many Vortex customers come from industries where conveying abrasive material is a recurring challenge.  Configuring the appropriate slide gates and diverter valves for those customers is a challenge in its own right. In this article, we’ll analyze the key factors that influence the decision of which slide gate or diverter valve works best for handling abrasive materials.

Different Levels of Material Hardness Cause Different Levels of Wear

Abrasion occurs where the metal components of a valve are worn down by friction as handled materials impact those areas. Prior to assessing what type of gate or diverter is most appropriate for the application, special consideration must be given to material characteristics and how the material is being conveyed.

Minerals are categorized by a Mohs hardness scale. The scale characterizes the scratch resistance of various minerals by observing how easily a harder material can scratch a softer material. Softer materials, such as talc, have a Mohs hardness rating of 1, while harder materials, such as diamonds, have a Mohs hardness rating of 10. When selecting metal valve components, it’s important to select the proper construction materials that can resist the hardness and wear of the material handled.

Material Shape Has an Impact on the Effects of Abrasion

The shape of the material being handled is another important consideration. Sand can have a Mohs hardness rating of 7, and exists in a variety of shapes. Some sand particles can be round, while others can be angular. An angular particle will abrade valve components much faster than a rounded one.

How the material is handled is yet another consideration. For example, is the material being gravity-fed through the valve, or is the material being conveyed pneumatically through a system at 3,000 feet per minute? Talc, one of the softest minerals, can eventually chisel its way through a substantial metal plate if given a small exit hole and considerable force behind it.

Hard Metal Wear Liners can Alleviate Component Breakdown

Utilizing hard metals or metal alloys for the wear areas is always a consideration. Valves may be manufactured to incorporate abrasion resistant plates, chromium carbide overlays, or metals like Hastelloy® to reduce wear from material abrasion. Diverters may also be manufactured with replaceable wear liners, typically constructed from the above-mentioned materials.

Replaceable Abrasion Resistant LinersOver time, worn liners may be replaced with new ones. This extends a valve’s life cycle and reduces costs by allowing replacement of parts, rather than full-valve replacement. In certain applications, an additional valve feature as simple as an interior rock box may be added to address abrasion and prolong valve life. A rock box is an area within the valve designed to trap small amounts of material while subsequent material traveling through the valve impacts atop the trapped material, as opposed to abrading a liner or plate. When material cross-contamination is not of concern, this feature is extremely effective.

Manufacturing Experience with Abrasives is Critical

Companies that deal with abrasive products are cognizant of the fact that new equipment begins to wear quickly, starting day one. Equipment installed in these environments must be continuously maintained. Sourcing valves from an established supplier with the ability to provide support after installation can help alleviate the burden of dealing with challenging applications. Supplier expertise can address the many challenging factors experienced in unique applications, and can assure your company is purchasing the best slide gate or diverter valve available for handling abrasive materials.

Orifice Gate vs. Butterfly Valve vs. Bull Nose Knife Gate: What are the Differences?

Material Type

One fundamental difference when comparing the Vortex Orifice Gate to other valves, such as a butterfly valve or a bull nose knife gate, is the Vortex Orifice Gate is specifically designed to handle dry material, while the other valves are not. Butterfly valves and bull nose knife gates are designed for gas and liquid applications. They are effective valves in those environments, but suffer numerous problems when misused in a dry bulk handling application.

Butterfly Valve Deficiencies

Rotating Disc in the Material Flow Stream

The butterfly valve’s design creates a handling problem for dry bulk solids, as the disc is located in the immediate material flow stream, creating significant flow restriction. Many process engineers design their entire conveying system with larger than necessary piping to accommodate these bottlenecks created by butterfly valves.

Soft Seals which are Exposed to the Material Flow Stream

The soft seals in a butterfly valve allow the rotating disc to produce a bubble-tight seal in the closed position. The very nature of dry solids does not allow these types of valves to create a tight seal because dry material cannot be displaced like a gas or liquid. Many issues can arise over time as the seals begin to erode and tear. Butterfly-Valve-Damaged-copy

The soft seat of the butterfly valve is also susceptible and exposed to the material flow stream. This causes additional wear points and eventual leakage of conveying pressure and/or materials through the valve – even in the closed position. In powder handling applications, material particles tend to migrate through the stem of the butterfly valve, causing the valve to seize.

Bull Nose Knife Gate Deficiencies

Bull nose knife gates would seem more logical for dry solids handling than butterfly valves. However…

Lack Seal Durability

Because bull nose knife gates are also intended for handling gases and liquids, the soft seals typically used in them are also exposed to the material flow stream – which is problematic when handling dry material. Upon gate closure, the leading edge of the blade tends to compact dry material into the soft seals, causing seal abrasion and preventing the valve from fully closing. In the bonnet area of a bull nose knife gate, a packing gland seal is designed to prevent conveying pressure and materials from escaping into the atmosphere. As dry materials migrate through the packing gland seals on opening and closing strokes, the seals are also exposed to abrasion. Once the packing gland seals are worn, conveying pressure and materials are able to escape into the atmosphere.

Butterfly Valves & Bull Nose Knife Gates: Shared Deficiencies

Rebuild or replacement can be cumbersome with both valve designs, as they are generally constructed as heavy, metal castings. This adds a significant amount of unnecessary weight to the valve, making it difficult to install. Also, because metal castings are solid objects, they do not allow interior inspection and/or maintenance to be performed while the valve remains in-line. Inability to perform quick maintenance requires plant downtime – and in some cases, it is cheaper to replace the entire valve instead of maintaining seals and parts.

Benefits of the Vortex Orifice Gate

These problems are eliminated in the Vortex Orifice Gate design. It utilizes a sliding blade constructed from rectangular stainless steel plate with a round orifice machined through it. The sliding blade actuates between two compression-loaded hard polymer plates. In the closed position, the compression load on the blade prevents conveying pressure and materials from migrating passed the blade or escaping into the atmosphere. In the open position, the blade’s machined orifice aligns with the conveying line, eliminating flow obstructions and exposed seals – which are vulnerable to wear from the material flow stream in the butterfly valve and bull nose knife gate designs. The Orifice Gate also “self-cleans” material from the seat on each opening stroke of the blade, so there is no material packing or bridging.

The Orifice Gate’s compression-loaded hard polymer seals compensate for wear, unlike the butterfly valve and bull nose knife gate designs. This extends the service life of a valve and requires less maintenance. The compression load on the seals is also adjustable. By loosening the nuts along the lateral aspects of the gate, shim(s) can be removed and the nuts retightened to restore the gate’s dust-tight seal. Because this maintenance procedure can be performed while the valve remains in-line, downtime costs are reduced.

If the valve ever does need to be removed from the conveying line, its construction is lightweight, compared to cast valves.

What Qualities to Look for in Diverter Valves used in Extreme Wear & Abrasion Applications

…a Q&A with Kevin R. Peterson, Regional Director of Business Development, Vortex 

Q. We are conveying foundry sand and our diverter valves wear out too frequently. What qualities should we look for when replacing these valves?

A. A wide range of diverter valves is available for handling abrasive materials, such as sand. It is important that all of your application parameters are addressed to be sure you choose the appropriate diverter, equipped with the necessary abrasion-resistant modifications.

One philosophy is to construct the internal material contact points from abrasion-resistant (AR) materials. Examples include AR plate or ceramic. The purpose for using these more durable materials is to decelerate the wearing process.

Another approach is to incorporate dead pocket areas into the material flow stream. These dead pockets fill up with material, creating an area where material impacts on itself—protecting the valve from additional wear. Do note: dead pocket areas should only be considered for applications where material cross-contamination is not an issue.

When considering wear modifications to existing diverters, it’s important that the parts are easily accessed for future replacement. This will provide tremendous maintenance cost savings. Selecting a manufacturer with proven experience in designing and manufacturing diverters for handling abrasive material is key to ensuring favorable life-cycle equipment costs.