The APEX Modular Regulator - Why We Do it Different!

With anything that relies on mechanics, everything that changes has an impact on something, if 'it made no difference' then you just aren't looking in the right place. Many of the details that we have designed/developed over the years come down to small incremental changes to many parts, but all these changes add up, and soon enough the differences are very apparent as the 1% snowballs into new areas of performance.
Why are the springs so important?
Belleville washers or disk springs as they are also called, compress under load and forces to be distributed along a length, governed by the arrangement of the springs, allowing a set movement. Depending on what is required, in our case allowing travel of the piston to be altered, ultimately setting the regulator pressure when the piston meets the adjuster and the regulator closes. This relationship not only sets the output pressure of the regulator, but influences how sensitive the adjustment is over the working pressure range, and governs how accurately the regulator cycles when fired and how quickly and precisely it refills after the shot is taken. These last two factors are very important to how the regulator performs.
Too fast or too slow?
A regulator that refills too quickly can allow a differing amount of air (depending on the fill pressure) into the plenum as the firing valve is trying to close, this can cause strange shifts in power output over a fill, with a steadily rising or falling Muzzle Velocity (MV) depending on how the rifle is set up. This rapid refill also wastes air leading to a loud, air hungry rifle.
Equally, a regulator that refills the rifles plenum too slowly can cause any secondary follow up shot, such as rapid-fire situation to have varying velocities. This is often caused by regulators that have very little piston movement, little air flow, or a very large sealing area and takes a long time to seal, which effectively gives a type of 'short term' regulator creep, sometimes taking 5-10 seconds to seal and reach a stable output pressure.
Excluding semi auto airguns with large flow, which use the regulator more like a restriction than a 'cup' of air to feed to the pellet on firing, ideally the regulator wants to refill in 2-3 seconds. Upon firing the firing valve/regulator plenum shouldn’t be completely exhausted. If it is, this reduces any pneumatic closing benefit of the valve by the post firing pressure in the plenum. Causing the valve to rely solely on any valve spring to close the valve, which can again lead to a very air hungry rifle. Using as little air as possible in the firing cycle is key here to give the best overall benefit. More on that in our other Guides.
Sensitivity
A good regulator should be able to accommodate the expected pressure drop on firing from your rifle and reset itself accurately every time, in any situation. ‘Over sprung’ regulators have very course adjustments, sometimes going from 0 bar to fully open in a ¼ turn of the adjuster. This micro movement often means the regulator piston has minimal movement when the regulator cycles, which gives long refill times and the sealing area becomes a trap for any debris that will eventually cause regulator creep issues as the seal becomes damaged, and no longer provides a clean seat for the piston to seal onto. Eventually this leads to regulator creep due damage of the piston face and adjuster seal.
Very highly sprung designs also makes the regulator very sensitive to thermal changes, as well as mechanical wear of the regulator seal itself, even 0.1mm of deformation over a few hundred shots/cycles of the regulator on a seal with an overly sensitive regulator can change the output considerably, some we have tested gave a 60bar output pressure change rendering the rifle not fit for purpose due to soft materials used on the piston seal and too much spring force, overall a bad regulator design.
The APEX Regulator has been developed to give very fine adjustments, allowing you to accurately tailor the output, and allowing it to remain stable. This greater resolution and therefore larger piston movement for adjustment means the regulator is also far less sensitive to mechanical wear, temperature shift and any frictional losses within the Belleville stack having any impact on the output pressure of the regulator. All good things to keep you shooting consistently and accurately.
The other type of sensitivity to take into account in a regulator is the sensitivity the regulator has to the drop in pressure in the plenum/firing valve when fired. I won't get into the deep physics here, but regulators with very small piston areas have less force acting upon them from the air in the plenum, and therefore the ratio of spring force and the force applied to the spring by the air in the plenum in much less, if the drop in pressure is not significant enough, the regulator may not cycle as it is not sensitive enough to detect the force/pressure change. This often gives the symptom of a high then low MV shot to shot. Reducing the plenum area helps combat this, giving more pressure drop for the regulator to 'sense' but it is not usually a benefit overall to reduce plenum size unless it is being used to limit power output.
Stacking Up!
To negate as far as possible the spring stack shifting as the regulator cycles the APEX Regulator has a close tolerance piston to Belville fit. This is to prevent the 'shuffling' of the disk springs and influencing the output of the regulator which is a factor of overall consistency from the regulator output. Also, we recommend always having the ‘cup’ against the acting faces of the piston and adjuster housing to make the stack as mechanically stable as possible. This only makes a small difference to the overall consistency, but good mechanics is good mechanics, and you may as well work with it rather than against.
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Recommended
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NOT Recommended
Double stacking the Belleville washers can be done, any frictional changes/losses from shot to shot are minimal, however we suggest no more than 3 Belleville’s are stacked and they are stacked equally, the increased friction between the disks will prevent them from working effectively and can give variance in regulator output. Uneven stacking leads to additional stress on individual disks and will cause possible disk failure, inconsistency and unpredictable adjustments.
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Recommended
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NOT Recommended
Belleville disks are most efficient and stable with between 30% and 80% compression, above and below these levels the spring action of the disks is not optimum, as the material is not in it's most stable 'elastic deformation area', which can lead to inconsistency in your regulator output. Keep in mind the pressure of your regulator, and your plenum volume.
A rifle that takes 5 shots to empty the plenum completely with the air supply removed in front of the regulator will need a stack sensitive enough to pick up on that pressure change, allow the piston to move enough to allow air through and seal again. For example, from a 100bar set pressure and 1 shot taken, will reduce the pressure by approximately 20% to 80bar. (This figure is not exact but working on this theory works well in our testing). Selecting the right spring stack for your rifle is key to consistent and reliable results. Often the more shots you can get from a plenum, indicates how efficiently your rifle is setup, minimal air wastage, maximum use of the air, and les reliance on the mechanics.
Your APEX Regulator will come at a pre-set pressure for your rifle from the options you select so there is no need to alter the spring stack, but for information on adjusting your regulator have a look at our Guides page.