Air Gun Home :: View topic - Increased Safety Using 4500 psi ShoeBox for 3000 psi Fills

rsterne · Moderator

As anyone who has looked at a ShoeBox compressor knows, Tom will NOT discuss how to make it safer for 3000 psi fills on a 4500 psi compressor for legal reasons.... The 4500 psi compressor has a 7.5K burst disc and the 3000 psi compressor has a 5K burst disc.... I bought a 4500 psi compressor to go with my brand new Ninja 90 ci 4500 psi tank (thanks, Eric!) .... but I also want to be able to fill my 3000 psi 80 CF SCUBA tank with it.... Obviously, you can sit and watch it or use a timer, but what happens if you walk across the street and get hit by a truck while filling.... you don't want the tank to blow up taking the house, wife, kids, and dog with it.... Shocked

The ShoeBox comes with a male Foster output.... My 4500 psi Ninja tank also has a male Foster inlet, so obviously the hose has to have female Fosters both ends.... While I was at it, I put in a "T" fitting and a 5000 psi liquid filled gauge.... So much for the 4500 psi fill setup.... Cool

I have a standard "Fill Clamp" on my SCUBA that ends in a short hose and a female Foster which will fit on all my various guns.... Hmmmmmmmm.... Houston, we have a problem, two females don't work here (don't ask, don't tell).... The easy solution is to make a joiner with two male Fosters.... so why not put a 4.5K burst disc in the same fitting and then if all else fails, the burst disc will go and protect the SCUBA tank (which is hydrotested to 5K).... Here is the result:

First of all, let me apoplgize for the messy Teflon tape all over the place.... I'll clean it up tomorrow.... Embarassed

.... The hose on the left comes from the ShoeBox and ends in a female Foster and gauge.... The hose on the right is part of my SCUBA fill station.... The bit in the middle is the removable adapter with two male Fosters and a 4.5K burst disc.... I can't fill the SCUBA tank without using it.... Looks good to me.... Mr. Green

BTW, it's filling at just over 150 psi per hour on the 80 CF tank.... Cool

Bob

rsterne · Moderator

Here is a pic of the two compressors connected up and running.... The front cover on the ShoeBox is removed and the flash stopped the action.... Cool

This thing is fascinating to watch.... The 3 gal. Oil Free CT compressor is equipped with a regulator currently set at 85 psi and a water / oil / particle filter on the outlet.... The filter has a clear bowl and can be drained easily.... So far, not a sign of any water (over 2 hours)....

Bob

walter · Veteran Member

looks like to much stuff to fiddle with. Shocked

ill stick with my 97k. Laughing

fritz · Silver Status Member

Seems pretty simple to me.

Nice rig.

oddtodd · Silver Status Member

I'll stick to my crosmans. I would rather break the barrel. If I had the money to do that I probably would still stick to springers, because only 10 or 12 shots per reload isn't enough for my taste. I had a maurauder and hated it. good luck witbh it though.

rsterne · Moderator

packrat · Senior Member

Thirsty indeed..one of my Crosmans, a .177 AS2250 converted to HPA gets gets over 100 shots at 12.4FPE on a single 13 cu.in. bottle fill..... heck, even my AA S410 gets 30 shots per fill and it has a very small air reservoir (carbine version)
BUT, back to the OT..I guess I'm gonna have to break down and get on the list for a 4500 shoebox..from what I've seen and read about them they are THE THING for personal airgun requirements Mr. Green

rsterne · Moderator

The price is going up about 10% Jan. 1.... If you want one at the $390 price you have to be on the list by Dec. 31.... Tom will honour that price for anyone on the list by the end of the year.... Shocked

Bob

sniper · Silver Status Member

AirGunEric · Site Admin

I've had the Shoebox for about 6 weeks now- and have yet to power it up (no time). Now the Marauder is here, and my SCUBA tank could use some filling...

So- let me ask- the Shoebox has a 7K burst disc- could this be replaced with a 4.5k burst disc to eliminate some of the plumbing in Bob's setup (I like the gauge, but by the time I have the time to make an external adapter for the burst disc from the ground-up, I'll have more gray hair and Christmas will likely have come and gone again).

Along the same lines, the gauge- does the SCUBA yoke gauge not read accurately when filling, or is the in-line gauge there for a double-check?

rsterne · Moderator

You will have more luck finding a 5K burst disc than a 4.5K one.... and I see no reason you couldn't replace it.... You will probably find your SCUBA tank also has a 5K burst disc mounted in the valve anyway....

The gauge on the fill clamp will work fine.... I replaced mine with a 3500 psi gauge from a Hill pump so that is was easier to read accurately.... I have the 5K gauge on the hose because I use the same fill hose when filling my 4500 psi tank....

Bob

AirGunEric · Site Admin

OK- 5k burst disc on Shoebox it is! All these hoses. I think I will run one straight braided steel line from Shoebox to SCUBA tank.

Bob- how well does the "adjuster" on the Shoebox for shutoff pressure work? I noted mention of it in the instructions, but it seems a bit less than precise.

rsterne · Moderator

Moving the collar to the right increases the pressure.... However, "less than precise" is absolutely correct.... The input pressure from the shop compressor factors in.... The higher the pressure, the sooner the ShoeBox shuts off.... then you add in how the tank pressure varies in the shop compressor.... My CT shop compressor shuts off at 100 psi but doesn't kick in until 70 psi.... If I set the regulated output at 85 psi (as recommended for the ShoeBox) then the actual pressure at the ShoeBox spends 50% of the time at 85 psi and 50% of the time lower (as low a 70 psi).... That affects the shutoff pressure for the ShoeBox....

The only way to get a (more) consistent shutoff pressure for the ShoeBox would be to have a shop compressor that cycled from, say, 90 psi to 120 psi.... and then set the regulator pressure below the "kick-in" pressure of the shop compressor.... Then the ShoeBox would always see the same input pressure.... and at least in theory shut off at a consistent pressure (adjustable by the collar)....

Bob