Login    Register
User Information
Username:
Password:
We are a free and open
community, all are welcome.
Click here to Register
Sponsored
Who is online

In total there are 64 users online :: 4 registered, 0 hidden and 60 guests


Most users ever online was 155 on Mon Aug 15, 2016 1:40 am

Registered users: Bing [Bot], Google [Bot], Google Adsense [Bot], Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

1,000psi pilot valve

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
Sponsored 
  • Author
    Message

1,000psi pilot valve

Unread postAuthor: saefroch » Wed Dec 01, 2010 4:21 pm

Just today I realized my pilot valve has acquired a small leak :(. This wouldn't be nearly such a concern if I didn't have a sealed piston, since it'd just be a leak. Now, if I let it sit around slowly leaking, eventually the valve will pilot. :shock: So I looked up the pressure rating for my current pilot valve, and it turns out that it's only 600psi. Whoa...

Would McMaster item# 4112T21 be a suitable replacement? Or should I look into steel and just steer away from brass entirely?
  • 0

User avatar
saefroch
Major General
Major General
 
Posts: 1679
Joined: Mon Jun 08, 2009 8:47 am
Location: U.S.A.- See Map
Country: United States (us)
Reputation: 0

Unread postAuthor: Fnord » Wed Dec 01, 2010 4:56 pm

The most logical thing to do in this case would be to pressurize it then take off the barrel and hide it in a co-workers desk somewhere.

...
That valve should be fine, but it depends on whether you want to spend $10 plus shipping on a 1/4" BV. If your piston pilots so easily, flow isn't to important but it might cause a slight delay. Hell, you could probably try a needle valve if you have any laying around.

I doubt steel has any real advantage in this case; it's all in the tolerances. Have you tried putting some thick grease in the ball valve? It can sometimes stop small leaks.
  • 0

Image
User avatar
Fnord
Major General
Major General
 
Posts: 2244
Joined: Tue Feb 13, 2007 9:20 pm
Location: Pripyat
Reputation: 7

Unread postAuthor: saefroch » Wed Dec 01, 2010 5:26 pm

Fnord wrote:The most logical thing to do in this case would be to pressurize it then take off the barrel and hide it in a co-workers desk somewhere.
Would be a great idea if I wasn't almost certain it'd leave a hole in the desk, if only from the recoil.

But anyway... I don't have any other valves laying around, sadly. The current pilot valve has taken such a beating from being used so far past its pressure rating, plus the vast amount of heat produced from compressing are probably just wearing it out.

No thick grease currently in my possession, unless I make something out of beeswax... :idea:
  • 0

User avatar
saefroch
Major General
Major General
 
Posts: 1679
Joined: Mon Jun 08, 2009 8:47 am
Location: U.S.A.- See Map
Country: United States (us)
Reputation: 0

Unread postAuthor: metalmeltr » Wed Dec 01, 2010 7:01 pm

what about a power washer handle
  • 0


metalmeltr
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 426
Joined: Thu Dec 18, 2008 3:42 pm
Location: united states
Reputation: 0

Unread postAuthor: saefroch » Wed Dec 01, 2010 7:12 pm

Power washer handle might be good. Do many power washers run at and above 1,000psi? Do they have NPT connections? Can one find a small power washer handle? It'd look silly unless it's pretty small...
  • 0

User avatar
saefroch
Major General
Major General
 
Posts: 1679
Joined: Mon Jun 08, 2009 8:47 am
Location: U.S.A.- See Map
Country: United States (us)
Reputation: 0

Unread postAuthor: Technician1002 » Wed Dec 01, 2010 8:04 pm

The slow leak may simply be dirt or something in the seal. Have you disassembled it for a cleaning? The brass ball valves can be opened and serviced.
  • 0

User avatar
Technician1002
Chief of Staff
Chief of Staff
 
Posts: 5190
Joined: Sat Apr 04, 2009 11:10 am
Reputation: 14

Unread postAuthor: Lockednloaded » Wed Dec 01, 2010 8:40 pm

You could use a paintball slide-check valve, they have 1/8" npt threads and can handle thousands of psi
  • 0

I love lamp
User avatar
Lockednloaded
Major General
Major General
 
Posts: 1558
Joined: Thu Sep 03, 2009 9:38 pm
Location: Texas, USA
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: saefroch » Wed Dec 01, 2010 9:02 pm

It's possible that it's a bit of teflon tape, but I'll check it out, and look for paintball slide valves while I'm at it.
  • 0

User avatar
saefroch
Major General
Major General
 
Posts: 1679
Joined: Mon Jun 08, 2009 8:47 am
Location: U.S.A.- See Map
Country: United States (us)
Reputation: 0

Unread postAuthor: DYI » Wed Dec 01, 2010 9:41 pm

Power washer handle might be good. Do many power washers run at and above 1,000psi? Do they have NPT connections? Can one find a small power washer handle? It'd look silly unless it's pretty small...


Not the greatest idea. Although some of them are rated up to 4000psi, they're made for sealing water "good enough", not for sealing air well. I bought a 4000psi one from McMaster which showed small leaks at even 500psi with nitrogen, and developed a very loud hiss at 2000psi. Pressure washer handles just aren't made to the tolerances necessary to seal high pressure gases.
  • 0

Spudfiles' resident expert on all things that sail through the air at improbable speeds, trailing an incandescent wake of ionized air, dissociated polymers and metal oxides.
User avatar
DYI
Lieutenant General
Lieutenant General
 
Posts: 2861
Joined: Sat Jul 07, 2007 8:18 pm
Location: The People's Republic of Canuckistan
Country: Turks and Caicos Islands (tc)
Reputation: 9

Unread postAuthor: velocity3x » Wed Dec 01, 2010 9:47 pm

saefroch wrote:It's possible that it's a bit of teflon tape.


Is the valve leaking at the stem seal? I find BV's tend to leak there after many cycles because the stem is so short and lacks bearings/bushings as stem guides. As a result, the stem seal gets chewed in time. If it's the stem seal, you can make one with teflon and a lathe quite easily.
  • 0

User avatar
velocity3x
Brigadier General
Brigadier General
 
Posts: 827
Joined: Fri Jun 05, 2009 3:09 pm
Location: Yuma, Arizona
Country: United States (us)
Reputation: 7

Unread postAuthor: Gun Freak » Wed Dec 01, 2010 9:51 pm

DYI wrote:Not the greatest idea. Although some of them are rated up to 4000psi, they're made for sealing water "good enough", not for sealing air well. I bought a 4000psi one from McMaster which showed small leaks at even 500psi with nitrogen, and developed a very loud hiss at 2000psi. Pressure washer handles just aren't made to the tolerances necessary to seal high pressure gases.


I find it hard to believe that a company would sell a product that didn't work well. It seems yours was defective, or damaged. In my mind, a leaky pressure washer handle would not be sold, especially if the company knew it was not a good product. A leaky pressure washer handle could potentially be dangerous.
  • 0

OG Anti-Hybrid
One man's trash is a true Spudder's treasure!
Golf Ball Cannon "Superna"M16 BBMGPengunHammer Valve Airsoft SniperHigh Pressure .22 Coax
Holy Shat!
User avatar
Gun Freak
Lieutenant General
Lieutenant General
 
Posts: 4969
Joined: Mon Jan 25, 2010 4:38 pm
Location: Florida
Country: United States (us)
Reputation: 11

Unread postAuthor: Lockednloaded » Wed Dec 01, 2010 9:59 pm

also DYI, don't lighter gasses such as nitrogen have more problems with leakage? I have heard of pressure washer handles leaking a tiny bit with unregged co2, but with just a small hiss
  • 0

I love lamp
User avatar
Lockednloaded
Major General
Major General
 
Posts: 1558
Joined: Thu Sep 03, 2009 9:38 pm
Location: Texas, USA
Reputation: 0

Unread postAuthor: the unit » Wed Dec 01, 2010 10:34 pm

Lockednloaded wrote:also DYI, don't lighter gasses such as nitrogen have more problems with leakage? I have heard of pressure washer handles leaking a tiny bit with unregged co2, but with just a small hiss


nitrogen leaks slower than compressed air, ever heard of tires filled with nitrogen?
  • 0


the unit
Specialist
Specialist
 
Posts: 51
Joined: Tue Jun 24, 2008 8:20 pm
Reputation: 0

Unread postAuthor: DYI » Wed Dec 01, 2010 10:44 pm

I find it hard to believe that a company would sell a product that didn't work well. It seems yours was defective, or damaged. In my mind, a leaky pressure washer handle would not be sold, especially if the company knew it was not a good product. A leaky pressure washer handle could potentially be dangerous.


Last I checked, pressure washers used WATER. Gases leak much more readily than water, as you should certainly know. The handle is of high quality, and performs admirably in its intended application. It is now in use by my neighbour, who needed a new handle, as it has been ever since I realized it was useless for my purpose.

also DYI, don't lighter gasses such as nitrogen have more problems with leakage? I have heard of pressure washer handles leaking a tiny bit with unregged co2, but with just a small hiss


Nitrogen (which comprises ~78% of air) has almost exactly the same propensity to leak as air, and CO<sub>2</sub> is useless as a propellant gas, and thus irrelevant to this discussion.

nitrogen leaks slower than compressed air, ever heard of tires filled with nitrogen?


While nitrogen may leak marginally slower than air due to a very slightly higher effective molecular radius, the difference is largely academic. It would be difficult to notice in practical applications, and the nitrogen filling for tires is essentially a scam with a flimsy scientific backing to charge people who don't know what nitrogen is $10/fill.
  • 0

Spudfiles' resident expert on all things that sail through the air at improbable speeds, trailing an incandescent wake of ionized air, dissociated polymers and metal oxides.
User avatar
DYI
Lieutenant General
Lieutenant General
 
Posts: 2861
Joined: Sat Jul 07, 2007 8:18 pm
Location: The People's Republic of Canuckistan
Country: Turks and Caicos Islands (tc)
Reputation: 9

Unread postAuthor: saefroch » Thu Dec 02, 2010 7:44 am

velocity3x wrote:Is the valve leaking at the stem seal?
No, it's leaking like I haven't fully closed it, not out the stem, but around the seal(s?). Both sides leak. I'm not even sure if my BV has a stem seal, but I'm not about to start tearing it apart without an understanding of how they're put together. I cleaned it out really well, and will re-grease and check for leaks when I get back this afternoon.
  • 0

User avatar
saefroch
Major General
Major General
 
Posts: 1679
Joined: Mon Jun 08, 2009 8:47 am
Location: U.S.A.- See Map
Country: United States (us)
Reputation: 0

Next

Return to Pneumatic Cannon Discussion

Who is online

Registered users: Bing [Bot], Google [Bot], Google Adsense [Bot], Yahoo [Bot]

Reputation System ©'