Choosing the right metering valve can be tricky. Even just calling it a metering valve has it’s issues. Some people call them grit valves, or abrasive valves. To be clear, we’re going to be going over the different types of valves on the market that go on your blast pot to meter or limit how much media/abrasive/grit goes into your air stream.
Disc Style Valves
Disc style valves include our Plana II and our Jr. Plana valves. They are also referred to as Flat Sand Valves. As the name infers, there is a disc inside these valves that has a hole in it. This disc sits on top of the valve’s opening. As you turn the handle, it turns this disc which moves that hole over the opening. This allows media/grit/abrasive to pass through the opening and into the air stream to blast with.
Adjustments are quick. Opening this valve just a little makes a big difference.
Imprecise metering. Hard to find the “sweet spot” and keep it there.
Plunger Style Valves
The next valve style is the Plunger valve. This would be our Fina Valves and Corsa Valves. As it’s name implies, there is a plunger in these valves that sits in a shaft. When a knob is turned, it raises or lowers the plunger in the shaft like a screw. This plunger, when closed, plugs the opening of the valve. When turned, the plunger raises and allows media/grit/abrasive to flow through the shaft and out of the opening and into the air stream to blast with.
Fine tuning of media. Small turns of the knob equal small movements of the plunger. You can really dial in the “sweet spot” with this set up.
Dialing in your abrasive mix may take some time.
What can we say about ball valves that you don’t already know! You probably have one or several of these valves on your blast set up already. They are used to turn on and off the flow of air from the compressor. They’re also often used in water applications. You can even use one as a metering valve if you needed to. Just like other applications, all you need to do is turn the handle to open or close the valve. This starts the flow of media/grit/abrasive into the air stream to blast with.
This is the least expensive of the metering valves. They also come in all sorts of sizes.
Metering with this valve is very imprecise. Small adjustments create huge differences in media flow which could waste valuable media.