MQ-Valve General Information
What is it?
The MQ Valve is a solenoid operated pilot actuated poppet valve. It replaces the main valve in an Autococker or knockoff.
Why Buy it?
The valve has two main selling points. It reduces reciprocating mass by removing the hammer that would normally need to be recocked by the backblock. The reduction in reciprocating mass results in a faster gun with less recoil. The valve also reduces lock time to around 4 ms. You can feel a big difference in lock time between an mQ-Valved cocker and a spool gun such as a Shocker. It almost feels like it shoots before you pull the trigger.
You can expect around 1600-1700 shots per 68/45 tank. Operating pressure is 200-300 psi.
Where to Buy
What Type of Valve Do I Have and Where Can I Find Troubleshooting and Technical Information?
I now have two separate pages for the mQ and MQ2 valves. These pages are largely duplicates, with certain wording and details changed to reflect the different valves.
PBX mQ-Valve - Identified by either blue or silver aluminum parts, with an exposed silver colored solenoid in the pilot, and an o-ring on the front of the poppet.
MTX Designs MQ2-Valve - Identified by red aluminum parts, a totally enclosed pilot assembly, and a urethane disk on the front of the poppet.
Buying a Used Valve
I would not recommend buying a used PBX mQ-Valve, especially the silver colored ones, unless the price is very low. These valves were very easy to damage and often were defective from the factory. You should be willing to pay a slightly higher price for the American blue/brass valves, as they are higher quality than the silver Taiwanese units. The solenoid should be inspected carefully to be sure the back cap is not pushed in and the wires are intact. I can't really suggest anything to find leaks other than pressurizing the valve and firing it. Also be aware that spare parts are generally not available for PBX mQ-Valves.
A used MQ2 would be a much better bet as many of the failure points on the older valves have been fixed. The only thing to inspect other than pressurizing the valve and listening for leaks is the wires. Make sure they are intact, because the wires are easily damaged while installing and removing the valve. Although MQ2 valves are generally pretty solid, some of the poppet seals have failed. Again, a leak test is critical.
As a comment on life in general, I've noticed that there are a lot of complete retards in this world that are incredibly talented at screwing up everything they touch. Precision machined components usually don't stand up well to vise-grips and dremels. Buyer beware.
A Brief History of the MQ and its Current Status
The PBX mQ-Valve was originally produced by a company called PBX Ballistix Lab LLC, owned by Mel Maravilla, Mike Quinn and myself. The patent was sold to National Paintball Supply. The first production run, consisting of approximately 130 valves with brass valve bodies and blue aluminum components was made in the USA with the exception of the poppets and assembled under my supervision. After this run, Mike and I split off from PBX due to disputes over Mel's operation of the business. Later production consisted of two runs of 500 Taiwanese made valves, which were of considerably lower quality. These valves were entirely made of clear anodized aluminum and tend to have issues with sticking poppets and leaks. PBX went out of business and Mel went into hiding after the second run of 500. Quite a few people who sent their guns in for repair never recovered their property.
A year or so later, Mike and I formed MTX Designs LLC, and I purchased a CNC turning center to restart production of the MQ. Our new valve, the MQ2-Valve, is a partially redesigned version of the old valve. We made changes to increase reliability and manufacturability. These new valves are 100% American made and should be much higher quality than previous runs. Here's the old progress page for the first production run. For the curious types, MTX doesn't actually stand for anything. I came up with those letters randomly by mashing my hand on the keyboard.
Spare parts and support are available for the MQ2 valves through mqvalve.com. We are not providing spare parts or warranty service for the PBX valves, although many of the MQ2 components and assemblies are compatible.
Design Changes and Parts Compatibility Between the mQ and MQ2
There were two major design changes made to the MQ2 valve. The pilot was changed to a fully enclosed unit with pilots matched to groups of solenoids and the poppet front seal was changed from an oring to a urethane disk. Changing the pilot to a fully enclosed design is obviously to prevent crushed solenoids and wires sheared by rotating solenoids. We decided to match pilot housings to solenoids grouped by lift, eliminating the orifice plate, thus allowing us to keep the same parts count and eliminate a cross drilled and tapped hole. A bevel is added to the wire slot during the deburring process and heatshrink is applied to the wires to reduce the occurrence of sheared wires. The change to a urethane disk seal actually increases parts count due to the vented socket head capscrew and washer necessary to secure the seal, but we felt this change was worthwhile to eliminate the often troublesome dovetail oring groove. Our experience in other applications has shown that the urethane disk and knife edge valve seal design is very robust. It has the added benefits of a reduced poppet head diameter to increase flow, as well as reducing the diameter of the back of the poppet due to reduced sealing force. Valve bodies are now brass again, because it has better friction properties and less tendency to form burrs than aluminum. The latest version of the MQ2 (referred to as rev. 2) has roller burnished valve bodies. This provides a hard mirror-like surface in the valve body bore, which will reduce sticking and wear on orings. The solenoid plunger seal was switched to 90 durometer urethane, which appears to seal at higher pressures.
The vast majority of MQ2 parts are not compatible with the mQ, however, the assemblies are interchangeable. MQ2 valve body assemblies (valve body and poppet) can be used with mQ pilots and spacers without modification. An mQ pilot can be replaced with an MQ2 pilot, but the MQ2 pilot is shorter and will require an MQ2 spacer. The solenoid and associated parts (plunger, spring, urethane dot) are completely interchangeable. The poppet spring and all orings have remained the same in both designs.
How it Works
The valve is quite simple in its operation. When the solenoid is energized, it lifts the plunger venting the back of the valve body. Since the hole in the pilot has much more flow than the hole through the poppet, pressure behind the poppet drops quickly. The inlet pressure forces the poppet backwards, releasing a burst of air. The plunger closes, then the back of the valve body refills with pressure through the hole drilled through the poppet, closing the valve with the help of the spring.
The spring is necessary to get the poppet moving when the pilot closes. A light spring results in the valve not closing at all.
Note that the poppet is never actually balanced because the hole through the front of the valve is .296" and the poppet bore is .406". Preproduction units had issues with the front oring not sealing because they were too balanced. The back bore was reduced to the original .375" in the MQ2, because the urethane disk requires much less force to seal on the knife-edge.
The graph above is two pressure transducer readings from an early prototype of the valve. The top trace is the pressure at the valve. The bottom trace is pressure at the breech. The oscilloscope was triggered on the positive slope of the solenoid signal. Pressure is 100psi/V. Input pressure was 300 psi for a 300 fps velocity. From this graph, you can see that the lock time is approximately 4.5ms and that the entire cycle of the valve is over in around 10ms. This gives a theoretical fire rate of 100cps. The characteristics of the current valve are slightly different, but I lost all of the newer graphs in a hard drive crash.
This unorganized chart is from an efficiency test performed on a current design mQ-Valve. E/Pd is an energy conversion efficiency number. It doesn't have any particular units but is calculated as V^2 / pressure per shot. Velocities and pressure drops were calculated over 10 shots. Entries with cp reg were run with a regulator attached to the ASA as a volume chamber. Entries marked oring are a comparison test between no -014 oring on the valve body and with the oring.
The results clearly show that running an excessively long dwell and low pressure do not result in good efficiency. It also shows that having some extra volume attached to the ASA significantly improves velocity. The last set of results show that the -014 oring around the valve body provides a huge increase in velocity. In the case of the PBX Frame, the air leaking around the valve with no oring is enough to kick the trigger forward, resulting in massive trigger bounce.
Keep in mind, that shooting fast will lower the efficiency by a large factor. An early efficiency test we performed confirmed this.
Optimum Performance of MQ Valved Cockers, Regardless of Valve Type
When building an MQed cocker, the best performance is obtained by reducing reciprocating mass. The bolt/backblock combo should be as lightweight as possible. I'm not familiar with the various products in the marketplace, so I can't make any specific suggestions. An aluminum or titanium pump rod is an excellent way to reduce reciprocating mass. Fatigue strength is the key factor here. Titanium has a much higher fatigue strength than the aluminum used in commercially available pump rods. The aluminum is lighter, but tends to break. The best solution is a pump rod made of high strength aluminum alloy, such as 7075. I don't think these are available commercially. For example, the PBX Rocker uses a bolt and shuttle block made of delrin and a short 7075 pump rod for a reciprocating mass of approximately 25 g (not including the ram shaft).
According to our tests, the best performing type of ram is a 5/16" bore run at 80 psi. A close second (by about .5ms) is the standard 3/8" bore at 60 psi. Speed did not increase with pressures higher than 80/60 psi. The real advantage to the 5/16" bore is that it uses a little less air than the 3/8". ANS sells a 5/16" Clippard ram with the required 6-32 threads (an uncommon feature in the industrial world) on the shaft. You can get the 1" stroke, 5/16" bore, 5/16"-24 nose thread, with bumpstops from most pneumatic cylinder suppliers (ex. Clippard [online ordering] and Bimba). Unless you are making your own pump rod, you'll have to purchase a unit with an unthreaded shaft and thread it 6-32 yourself. Run QEVs on both ports of the ram and use hose barbs with the biggest hole you can find. SMC makes some very nice 10-32 barbs with a large bore, but they're a little difficult to get and easy to break.
Some users have reported that polishing the inside of the valve body to a mirror finish improves consistency and gets rid of first shot drop off. I would recommend using a slotted wooden dowel in a die grinder starting with 400 grit paper. Work your way up to 2000 grit, then use a piece of paper towel soaked in Mother's Mag and Aluminum polish. MQ2 bodies have a better finish inside and little o-ring compression, so don't overdo it with the lower grit paper. This is unnecessary in the latest (rev. 2) version of the MQ2 valves, as the bore of the valve body already has a mirror finish.
Summary- Light backblock and bolt, titanium pump rod, ANS ram with QEVs
Why is it Called mQ? What Did Kerry Johnson Do?
mQ stands for Mike Quinn, the guy who came up with the idea. Mike has a masters degree in mechanical engineering from Stevens Institute of Technology and works full time for BD. My role in the project was making prototypes, designing and building test and measurement equipment, and general helping tweak the valve. Unfortunately, I ended up handling the shipping of orders in the first batch.
last update: 2/11/08