Help one more time.

[kentek314]

Kentek the newbie here again.

Final part arrived today that should allow me to use my filling station. My last required partwas the bleed valve as some of you so graciously pointed out. Why should that be so hard to find.One on Amazon out of stock...maybe forever. Others bloody expensive.

So, I found something on AliExpress. $23 inc. ship. Just had to wait for it to get here. Looks like it is well built, nice gauge, hose, and fittings all pretty trim. BUT...

Not sure about the key function of this device: how does it bleed the high pressure air? Just a big-assed bolt with a knob on it. No air release hole. Looks like the way it closes is that it totally blocks off a small port internally. Then, to release the air, you open the valve and the air escapes via the loose bolt threads.

Does this seem like a safe enough device to manage 2900 PSI which is my desired pressure point? I think I need to be careful to not let the bolt fall out of it bolt hole.

What say you guys?

Thanks again,

Kentek

I

 

[vinny]

can you upload a pic of what you have ? 

 

[marflow]

but all your doing is bleeding the hose so you can remove it from the fill port

 

[airgunfans]

Looks like the way it closes is that it totally blocks off a small port internally. Then, to release the air, you open the valve and the air escapes via the loose bolt threads.

Does this seem like a safe enough device to manage 2900 PSI which is my desired pressure point? I think I need to be careful to not let the bolt fall out of it bolt hole.

You are absolutely right. Bleed valves work in that way and it's a very simple device. Air escapes mainly via a small channel cut on the bolt or it's housing instead of the threads.

The one in my Yong Heng set up routinely stands 4500 psi with no problem. I don't worry about safety at all because all the threads must be stripped simultaneously before the bolt or it's housing can fly out like a bullet. The force required is tremendous. The internal port hole is just too small to allow such force to be generated. 

Just a tip : do not over tighten the knob of the bleed valve or you will run the risk of pushing the bolt through the internal port which is just a hole on a plastic washer. If the valve is normal, just a little force is required to close it securely. 

 

[Bigragu]

It sorta works the same way as the petcock drain at the bottom of your cars radiator. On my compressors bleed out screw, it is basically a smaller screw inside a threaded 1/8” bsp fitting. The 1/8 threads into the block and seals against the delrin washer. When I unthread the actual bleed screw out of the 1/8” BSP fitting, the end of the bleed screw has a tapered point at the end, that seals against the inner doughnut hole of the delrin washer inside. So basically it seals off by a taper fit. One little turn counter clockwise pulls the tapered point away from the delrin doughnut hole and then it goes PPPFFFFFFTTTTT!!!

 

[kentek314]

Yep, you are correct. I was making this way too complicated.

You cleared my fuzzy thinking.

Thanks.

kaw

 

[kentek314]

One last item:

Is is recommended to ue neoprene/plastic tape on all connections?

 

[airgunfans]

One last item:

Is is recommended to ue neoprene/plastic tape on all connections?

I believe you are referring to teflon tape. They are essentially lubricant and does not seal except for when used on tapered threads. On parallel threads, they can prevent seizure and make it easier to break joints loose so there is some benefits . Anyway, I don't use any in my Yong Heng set up. 

 

[Bigragu]

 



If ever I need to use a Teflon tape, it is usually on NPT connections. BSP connections usually come with a dowdy seal or an inner delrin doughnut seal. Anyway, I’m a big fan of putting a thin coat of Nylog red on any threads that use a Teflon. It’s use was designed for the HVAC industry, dealing with high pressure refrigerants. It is an o ring conditioner, handles heat well, resistant to oils, and the best part, you can take apart the fittings years later and it’ll feel like you took it apart tight after you assembled it. I always use it on my trucks transmission line fittings, as an added defense against leaks, or any high pressure water systems using PVC so I don’t have to take that extra 1/4 turn to tighten and risk snapping the fitting. 

As as an example, the bolt on my palm is the oil drain plug for my Lightning compressor. I did not add any Teflon tape, just applied a light coat of Nylog on the threads that will be in the threade section of the case, not in the oil stream, so close to the allen head. I had no leaks whatsoever.