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Your abrasive metering valve is among the most important components of your blasting set-up.
This valve’s importance is often dismissed and contractors unknowingly lose efficiency and profit because they are wasting pressure and abrasives – not to mention jobsite downtime and continual repairs.
The following information is designed to help you understand the importance of your metering valve and make the right buying choice for your operation.
| Pressure System | Best Scenarios | Multiple Blasters? | Min Pressure Required | Benefits | Disadvantages | Retrofit | |||
|---|---|---|---|---|---|---|---|---|---|
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SCHMIDT THOMPSON I VALVE | Pressure-Hold |
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Yes | 80 psi |
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SCHMIDT THOMPSON VALVE II | Pressure-Hold |
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Yes | 80 psi |
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Retrofit Kit | |
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SCHMIDT THOMPSON 2 XL (Extended Life) | Pressure-Hold |
|
Yes | 80 psi |
|
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||
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SCHMIDT TERAVALVE XL | Pressure-Hold |
|
Yes | 75 psi |
|
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Retrofit Kit |
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|---|---|---|---|---|
| SCHMIDT THOMPSON I VALVE | SCHMIDT THOMPSON VALVE II | SCHMIDT THOMPSON 2 XL (Extended Life) | SCHMIDT TERAVALVE XL | |
| Resulting Pressure System | Pressure-Hold | Pressure-Hold | Pressure-Hold | Pressure-Hold |
| Best Scenarios |
|
|
|
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| Can Serve Multiple Blasters? | Yes | Yes | Yes | Yes |
| Minimum pressure required | 80 psi | 80 psi | 80 psi | 75 psi |
| Benefits |
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| Disadvantages |
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|
| Retrofit | Retrofit Kit | Retrofit Kit | ||
| Pressure System | Best Scenarios | Multiple Blasters? | Min Pressure Required | Benefits | Disadvantages | Retrofit | |||
|---|---|---|---|---|---|---|---|---|---|
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FLAT FSV ABRASIVE METERING VALVE | Pressure-Release |
|
No | No | Inexpensive |
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DONUT ABRASIVE METERING VALVE | Pressure-Release | For use with coarse metallic abrasive – typically blast room or bridge blasting scenario | No | No | Inexpensive |
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SCHMIDT MICROVALVE | Pressure-Release |
|
No | No |
|
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SCHMIDT MICROVALVE 3 | Pressure-Release |
|
No | No |
|
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Retrofit Kit |
|
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|---|---|---|---|---|
| FLAT FSV ABRASIVE METERING VALVE | DONUT ABRASIVE METERING VALVE | SCHMIDT MICROVALVE | SCHMIDT MICROVALVE 3 | |
| Resulting Pressure System | Pressure-Release | Pressure-Release | Pressure-Release | Pressure-Release |
| Best Scenarios |
|
|
|
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| Can Serve Multiple Blasters? | No | No | No | No |
| Minimum pressure required | No | No | No | No |
| Benefits |
|
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|
| Disadvantages |
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| Retrofit | Retrofit Kit | |||
If you’re a project manager or site foreman – here’s an important question you should find out if you don’t already know. What generation of abrasive metering valve do you have on your blast pots?
It may surprise you that your metering valve is one of the most significant indicators of your efficiency and profit. This is one of the most important (yet neglected) considerations on the majority of jobsites we visit. It’s so important in fact – that if you’re a project manager looking to turn ONE DIAL to improve your team’s performance – we suggest investigating your abrasive metering valve. It’s to your financial advantage to understand the metering valve you’re using and why it’s most likely costing you hundreds of dollars a day in inefficiencies.
First… here’s a general layout of the abrasive metering valves currently in use. These are listed from least efficient to most efficient across the broad range of blasting applications.
So, what makes one metering valve any better than another? ONE metric. Which valve saves you the most money? And this metric should be evaluated on the following 4 criteria:
We’ve explained these costs in a previous Primed Insight if you’d like to learn more. But suffice it to say, thousands of dollars can be lost each day simply by saving $200 on the purchase of a cheap metering valve. This is something every project manager should pay attention to.
A popular misunderstanding is all these valves represent different methods of metering. That is not correct. Each column is actually a generational improvement on the previous valves.
Think of the above valves through this perspective:
Engineering and materials have improved with each product upgrade.
Now, as we’re presented things, it may seem that the silver bullet to everyone’s problems is simply to buy this most current valve – The Axxiom Schmidt TeraValve.
And it probably is our top recommendation. It not only improves efficiency across the broadest range of industrial applications, but surprisingly, it also costs less than its predecessor – The Thompson 2 Valve.
However, for high flow jobs that use multiple #10 nozzles or in blast room situations using a robot, the Thompson 2 is actually our top recommendation.
Now in case you think we’re just trying to sell you a more expensive valve – here’s an insight within an insight…
Because we’re a business like you, profit and loss is something we must also manage. That’s why we have installed over 200 Tera Valves on our vast rental fleet. You can imagine that renting blast pots comes with quite a bit of maintenance and repair when they’re returned. We discovered that simply by installing Tera Valves on our rental pots, those maintenance costs dropped 75%.
THAT’S why we recommend TeraValves. They’re a superior product.
And in case you’re interested – this link leads to a Tera Valve retrofit kit so you can upgrade your current pot to the latest and greatest generation of metering valves.
If you have questions as to which valve is best for your pot and applications – just reach out and ask. That’s our job!
It may surprise you that this valve is one of the most significant indicators of your efficiency and profit. It affects the safety of your operators, how much abrasive you waste, and various pressure concerns. Rule of Thumb: The cheaper your valve costs on up-front – the more it will end up costing you in downtime, repair parts, wasted abrasive, and potential harmful accidents.
We only Schmidt Axxiom valves because they are the highest quality, safest, most efficient and reliable metering valves in the industry. Because they are of such high quality, Axxiom’s competitors are constantly producing knock-off valves trying to duplicate Axxiom’s superiority. But don’t fall for it. Buying knock-off valves will end up costing you much more in the end.
Each of our standard blast machines has the option of having a pressure hold system or a pressure release.
A Pressure Hold blast pot simply means that when the blasting operator releases the deadman handle to stop blasting, abrasive and airflow cease traveling down the blast hose toward the nozzle. However, the blast pot itself remains fully pressurized and ready to send the air and abrasive once the deadman is reactivate. Retaining blast pot pressure reduces the amount of time needed to commence blasting – because the operator doesn’t need to wait for the entire pot to repressurize.
A Pressure Release blast pot simply means that when the blasting operator releases the deadman handle to stop blasting, the pressure inside the pot that drives the air and abrasive is released into the surrounding atmosphere. This “depressurizes” the blast pot completely. This depressurization requires a bit more time to cut-off the flow of air and abrasive than a pot that retains pressure. Likewise, it takes a bit longer, once the operator reactivates the deadman, for the pressure to build in the pot to facilitate the flow of air and abrasive to the nozzle to resume blasting.
A Pressure-Hold system requires temporary shut-down of blasting operations to refill the blast pot with abrasive
We’re discussing the iconic combo valve from Axiom manufacturing today. This is a deadman valve which controls the air into, and the air out-of, your blast pot. It’s how your deadman works on a pressure release blast pot. That is a blast pot where the pressure is released out of the pot every time we stop blasting, versus a pressure hold where the pressure is kept in the blast pot when we stop blasting.
At the core of a pressure-release blast pot is this deadman valve called the combo valve and the reason is was the first valve in the industry to combine both the inlet which you see on this side and the outlet which you see on the other side into one valve.
There’s three key criteria in choosing a dead man valve for a blast pot. The first is safety. I’d like to go through the key safety requirements for the combo valve.
The first is that the air from the blast pot is exhausted through a piece of blast hose.
This is a failsafe aspect to this valve because it has a large spring it automatically when you lose pressure or something goes wrong this opens up and lets the air of the blast pot out.
The second thing is, because it has such a large piston and spring, it’s very fast active. That is very important because if there’s an incident takes place I need to make sure the blast pot shuts down as soon as possible.
The second key purchasing criteria for a Deadman control valve is productivity. The way to maximize productivity is to minimize pressure drop, and the way we do that with the combo valve is that as the air comes in to the bottom of the valve… travels up and through and heads on to blast, it passes through the valve itself.
Many valves have a restricted convoluted air passageway through the valve. Not the combo valve. It has a single plug that blocks the air and when it activates it pulls right out of the way and allows full and free airflow.
The third important criteria is how easy the valve is to maintain. How easy it is to use.
I’d like to point out two key benefits:
The first is the most common wearing part – is this hose. No need to rebuild the valve it’s simply a matter of refitting it just like you refit a blast hose. So that’s a very significant time saver.
Then if something goes wrong with the valve itself, it has what we call a unitized piston assembly – you see one here in my hand. It allows you to very simply undo four bolts, change-out the entire working center of the valve, put the four bolts back in, and be up and operating again in less than 10 minutes.
No need to pull the valve off the pot, no need to get out thread tape, no need to touch the piping. It’s a massive benefit to operators in the field.
Two things to remember: combo valve must be used with the Schmidt Deadman handle. They are designed to work together, and the use of non-standard or other brand Deadman handles is a safety hazard. And the last point is make sure you use genuine parts. It’s a safety requirement on every job site that genuine parts are used.
This has a major impact on the purchasing decision as to whether purchase a pressure hold or pressure release system. A pressure hold system is much quicker to activate and deactivate. The hold in the term pressure hold means when the deadman handle is released, pressure is held in the blast pot. The stopping of the blast is achieved by cutting the air coming into the pot (but not releasing the air that is already in there), air into the hose and abrasive into the metering valve. By holding the air already in the pot while blasting ceases, restarting the process is relatively quicker. It is quicker to shut down as well because it is not dependent on all the air being released from the pot to stop the blasting. Quicker system response is beneficial in stop/start blasting. Examples of stop/start blasting include: difficult access (working off scaffolding) and small parts requiring turning.
Some abrasive metering valves use a plate sliding across an orifice to meter abrasive flow. The problem with this is, that as the orifice is opened up, the volume of abrasive increases exponentially (i.e. the increase in increase increases). A system where a piston slides inside a cylinder means that the amount the abrasive increases in volume stays the same as the valve is opened up.
Either of these blasting tasks require a pressure hold system for faster stopping and starting of the blasting process. A Tera or Thompson Valve is the best valve for your application, giving you faster start/stop responses.
For powder coaters, who use abrasive with lots of the recycled “fines” we would recommend you use the Tera Metering Valve. This valve has the latest wear-proof technology of a wiper seal on the plunger, which allows it to be effective and give it a long life when using fine abrasive.
No metering valve is going to stand up forever against dust. Dust is the highest wearing particle that ever comes in contact with the valve.
You may require a pusher-line kit to connect the metering valve to the choke valve. This consists of a length of air hose and the fittings required to make the connection. This is because the new valve may have a different geometry to the old valve. This also an opportunity to replace the existing nipple that connects the valve to the blast pot (usually a standard water fitting) with a specifically designed blast pot connector. This is manufactured from an abrasion resistant steel, with the correct threads cut into it and has a tapered face on it to seat well down into the top of the valve. This connector protects both the pot and the valve. You may also a threaded quick coupling to go on the outlet of the valve to connect the blast hose to.
Look, listen and spray. The biggest cause of differential pressure is air leaks causing a pressure drop in the pot or the hose. An observant eye and an attentive ear will be your best tools for this. Be observant of changes in the behavior of your blast pot. A spray bottle with soapy water in it will and the soapy water sprayed onto the fittings and valves will create a stream of bubbles from the leak. Also check the hand-hole gasket and pop-valve when the pot is pressurized. If there is a pile of abrasive sitting in the dome it will “bubble” if the pop-up is leaking.
Generally speaking pressure release systems are simpler than pressure hold systems and consequently require less maintenance and are easier to work on. Take into consideration remoteness of your blasting locations and maintenance team experience when making an Abrasive Metering Valve purchasing decision.
There are many online videos at www.blastone.com on how to repair your metering valves, so if you know how to change the tire on your vehicle, you can easily handle repairing a metering valve (with the help of our videos)
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