Pressure and Lubricants

[CraigH]

I will be finally (multiple waiting for parts/materials and mistakes) performing final assembly of a 1322C that should be (at least I hope) notably more capable than in its stock configuration.   I thought I had a good understanding of the nature of the subject title, but now have a bit of confusion on the lube part due to a few things recently read.

The first is this from the Crosman Legacy 1000 description on Crosman website:
DUE TO THE HIGHER PRESSURES PRODUCED BY THE LEGACY, WE RECOMMEND RMCOIL FOR MAINTENANCE.
I read a post that stated the Legacy 1000 has a metal piston.  It otherwise appears to be a plastic receiver version of a 2100B and has only about 25 greater fps velocity with lead pellets.

The second is testing by rsterne on GTA:
http://www.gatewaytoairguns.org/GTA/index.php?topic=77463.0
There is seen pressures developed with stock plastic piston, stock piston modified with metal insert, and flat top piston.  The pressure possible with the FTP is substantial - 2500 psi at 40 pumps.   

Well, I am quite certain FTP setups are considerably more capable than the Legacy 1000.  So if the Crosman recommendation of silicon lube stands as accurate, such lube would be seen as necessary on higher powered pumpers.  BTW, a number of our vendors have their own lubes for sale which are no doubt excellent and acceptable, but I mention none to avoid slighting any.  And then there is RWS Air Chamber Lube - $$$$$.

I do not have any springers, but understand their near instant generation of heat and possible dieseling from over lubing or incorrect lubes.

I would think there is a time factor in the PVT (pressure-volume-temperature) equation of multi-pump pneumatics vs springers.  Could there be dieseling/oil issues in high powered pnuematics, I very much would think not, at least not the dieseling, but if so, then what about PCP's and HPA conversions?   I think the same extended time factor applies.   



Regarding the pressure, I have just pined the valve on the 1322C mentioned in the first sentence of this post, and I did so having a number of times read Gippeto's excellent sticky "Pining the valve for bulk/pcp. When, why, and how".  My understanding of the pumping action is this:

Given the pump arm and pump are fully retracted and the pump chamber is at atmospheric pressure and there have been previous pump strokes that have delivered some amount of pressure in the valve and the check valve is holding that pressure; the following occurs:

This next pump stroke begins compressing air and as the pump head approaches the valve at some point the pressure in the valve and the pressure in the pump chamber reach the same pressure and the check valve opens and the pressure in the valve and the pump chamber both then continue to increase until the pump completes its stroke and the check valve closes.  Each subsequent pump stroke repeats these events with each stroke having the pump head closer to the valve before the check valve opens.

So what is the pressure on the valve face while pumping and especially as the pressure increases to the point of opening the check valve and then increasing pressure in the valve?  I calculate it to be this when the valve, which is 0.625" in diameter, has previously been filled to 1000 psi:

(0.3125 x 0.3125) x 3.1416 x 1000 = 306.8 psi on the head of the valve.     And at 2000 psi it would be 613.6 psi on the head of the valve, and at 2500 psi it would be 767 psi on the head of the valve.

The valve may well be stable with the single added 8-32 set set screw pin (a la WyoMan's sticky) and the factory stake at the rear of the valve and grip screw, but for now I like having a bit more retention, at least if I try for substantial more performance.

Thanks for reading - the post is rather long.   Comments or corrections always welcome.     

[BillK]

This is what I use for lubing all the 13xx & 22xx guns.
http://www.mac1airgunshop.com/secret-sauce-small-dripper-2-fl-oz-p/m1ss2po.htm
If Tim says this is the best, who am I to disagree?

[CraigH]

Yes, it is one of three I have (plus Crosman pellgun oil).