Ninja Regs New Heavy Bellevilles

[rsterne]

I just opened up a recently purchased Ninja regulator and found a different Belleville Washer stack than I have ever seen before.... The reg. was marked 3000 psi input and 2000 psi output, and it was one with the new piston.... If you haven't seen one of these, the input end of the piston is tapered and the output side has two O-rings instead of only one....

Instead of the stack of twelve 0.032" thick Bellevilles I have seen previously in a reg set to this pressure.... this one had EIGHT 0.047" thick, plus one 0.032" thick and a couple of flat shims.... They were arranged....

|| ) () () () ()

The 0.047" bellevilles are VERY stiff, I would think that the 0.032" belleville would just collapse flat immediately.... so 0.032" of flat shims there would probably do the same thing.... Because of the extreme stiffness of the 0.047" bellevilles this regulator is VERY sensitive to shim changes.... Adding or subtracting 0.005" of shims changes the pressure by about 500 psi.... ie it's VERY fussy to adjust....

I think the older arrangement of twelve 0.032" bellevilles is much nicer to adjust.... in fact I took the heavy ones out and used the 0.032's because I needed to fine tune to 1800 psi.... However, if you need to build a regulator with a very high pressure output (over 2500 psi) this would give you the ability to do that.... McMaster Carr also sell these 0.047" bellevilles....

Bob

[PakProtector]

It is ov course a spring rate issue. The correct shim stack and a few .032 would have the same effect, but the travel would drop and it would flow less. Those washers are springs in series, so more of what ever spring constant they are drops the constant of the composite.

How do those shim stacks respond to a dry lube like moly disulfide?
cheers,
Douglas

[1377x]

do you have a pic of the new piston?
it sounds like thats what came in my tank i bought a couple months ago the bonnet or the sealing to the adapter part came with 2 o-rings instead of one but it was the 850psi out regulator

[rsterne]

Here is a little primer on Belleville washers (disc springs)....

A Belleville washer has several measurements.... thickness, free height, and flat load.... and also typical working height and load.... If you subtract the thickness from the free height, you have the maximum travel (to flat).... I have found that if you load them to the point of driving them flat (or reversing them, which can happen) the free height may be reduced, and the force may go down.... They also have a "spring rate" like any other spring, and in simple terms that is (flat load / maximum travel)....

When you stack them up, you don't change the force required to flatten each disc.... What happens to the travel and the spring rate depends on how you stack them.... There are two basic stacks.... series ) (  or ( )  and parallel  )).... In series you double the travel, same force to flatten, so the spring rate is half (in lb./in).... In parallel you keep the same travel but double the force to flattten, so the spring rate is twice as high.... If you do two parallel stacks in series )) (( or (( )) you have doubled the force to flatten AND doubled the travel, so the spring rate is the same as a single washer on it's own....

For the most part, I don't think the travel in a regulator is very important.... It might affect the flow rate, but basically as long as the regulator opens and closes at a given pressure it will do what we need.... There is one thing I don't think is a good idea when stacking Bellevilles.... Look at this stack.... )) (( ) (( .... If you put that under high load, the single disc could "reverse" as it only takes half the force to flatten it as the two-disc parallel stacks.... This will damage it.... If you need that height, you could do this.... )) (( )) ( .... The single disc would still flatten, but (assuming it was against a flat surface) it couldn't get reversed.... If you are pushing this arrangement to pretty heavy loads, however, you might be better to take out the single and just put in a flat shim of the same thickness.... )) (( )) | .... In practical terms there would be little difference, other than a bit less total travel from the "no-load" condition....

Ninja regulators use three thicknesses of Bellevilles (they used to use only two).... McMaster Carr sell these in spring steel and stainless, and the ones in the Ninjas are stainless.... I have no proof that they are identical to the McMaster Carr ones, but since the Ninja regs are American made, there is a good chance.... These Bellevilles are all 5/16" ID x 5/8" OD with specs are as follows:

0.022" thick, 0.042" tall, 105 lbs. flat (0.020" travel), 70 lbs.@ 0.010" deflection, installed height 0.032" (at that deflection)
0.032" thick, 0.048" tall, 260 lbs. flat (0.016" travel), 145 lbs.@ 0.008" deflection, installed height 0.040" (at that deflection)
0.047" thick, 0.059" tall, 600 lbs. flat (0.012" travel), 300 lbs.@ 0.006" deflection, installed height 0.053" (at that deflection)

Consider these stacks, at the "nominal" deflection above (ie half the maximum)....

0.047" .... ) () ( .... Force = 300 lbs.... Travel remaining = (4 x 0.006") = 0.024" .... Installed height = (4 x 0.053") = 0.212"
0.032" .... )) (( )) (( .... Force = (2 x 145) = 290 lbs.... Travel remaining (4 x 0.008") = 0.032" .... Installed height = ( 4 x (0.040"+0.032")) = 0.288"
0.022" .... )))) (((( )))) (((( .... Force (4 x 70) = 280 lbs.... Travel remaining (4 x 0.010") = 0.040" .... Installed height = (4 x (0.032"+(3 x 0.022"))) = 0.392"

Functionally, these stacks would all work about the same if installed with shims to the installed heights given.... They would all be very sensitive to shim height, however, as they are very "stiff".... I hope that gives you a basic idea of how Belleville washers work when stacked up in different arrangments....

Sorry, I don't have any pics of the new piston....

Bob

[1377x]

i was just wondering what the difference in looks of the pistons are since i have only one tank and the rebuild kit has the same piston as the one in the tank bought a couple months ago

[airpuffhunter]

very interersting, thank you for the info

ja I agree with the saved pages, I have a folder in favorites called airgun, wich is like 3-4 pages long