Male QD x 1/8” MNPT with built in check valves

[Bigragu]

I’m curious how many folks use these? Seems to be the fitting of choice to have closest to your tank when topping off, in case the fill whip or fill whip fittings decide to let loose, or worse yet, explode! If any of you have used these, I’m curious to know how well that check valve works in holding back the high pressure air.



other than mounting that as close as possible to a fill tank, where else have you used these? 

 

[T3PRanch]

All foster fill nipples I know of (used on tanks) are this configuration. Couldn't keep air in the tank or reservoir otherwise! Tanks and reservoirs are what the Check Valve fosters are made for.

 

[Eaglebeak]

I use one at the tank inlet and the pump outlet. There are a few other advantages in doing this. Bleeding the pump is more efficient and can be done without losing the air in the filter and lines. The one at the tank end, allows the valve to be opened before the pressure in the line has equalized, making that process automatic. At a couple of bucks each, they are cheap insurance.

 

[bandg]

All foster fill nipples I know of (used on tanks) are this configuration. Couldn't keep air in the tank or reservoir otherwise! Tanks and reservoirs are what the Check Valve fosters are made for.

Is this correct? Doesn't seem right to me but I'm certainly no expert. The reservoir has to have a one way check valve and the tank valve closes the other end. All foster nipples have a check valve in them?

 

[Humdinger]

No, all Foster's don't have check valves built in, but that's not what T3PRanch said. He said that's what Foster "check valves" are made for. If you look inside the Foster and can see through it then it's not a check valve. Some are made to be used as check valves and some aren't.

 

[B3ntong]

I use similar on my hpa bottles and QB's

 

[Eaglebeak]

I use similar on my hpa bottles and QB's

Yes, that is the type that I use. This is how they can be configured. The one in the middle can be used in either direction as an inline male to male connector. The left one is for a DIN 300 tank valve.the one on the right is a male to female and can only be used in one direction. About $24 USD for the lot.

 

[Bigragu]

Eagle beak, thanks for replying with assurance on these fittings. The one shown from that Zymkyfa is the one I ordered, but got thru Amazon in 1/8” NPT. I do have a question for you though in your pic with the 3 setups. That check valve built into the fittting allows air to flow from the QD end towards the threaded end, correct? That’s how I understand it, so say one of these are threaded into my din fitting for say topping off a tank with my compressor, and right at 4,000 psi the compressors fill whip explodes. My tank should not empty out cause the pressure would push on the inner check valve, which is going against the airflow path I described earlier. You with me so far?

so, in your pic, the middle and the one on the right. The air flow on the right fitting goes from the male QD end towards the female QD end, so yes, I agree that can only go one way. But on the middle set up, you say it can be used in either direction? 



I think for clarification, you meant it can be used in either direction, depending on its use, AT THE MOMENT. One still need to pay attention that the air flow will move towards the male QD that has the female threads. Am I making sense? The QD that has the male threads houses the check valve.



i apologize for complicating things. Jus wanted clarification, boss 

 

[Bigragu]

i recently ordered a few fittings, all in stainless steel, and all in 1/8” NPT. I am going to construct two set ups with 90 degree elbows, with a male and female QD at each end, to make filling my guns with moderators easier(PRod for sure), along with having a 90 right at the compressors discharge block on my Hatsan compressor, so that my whip can easily be removed when done, and also have the benefit of my whip having a swivel point. I’m going to tak your suggestion and mount one of these check valves right at the compressor, and right on my DIN fitting for tank fill ups.

 

[Eaglebeak]

No need to apologize. You have the right assumptions, the reason that the inline male to male can be used in both directions is by turning it around, it works the other way. You are right about having the stop valve as close as possible to the cylinder will avoid losing any air in the event of a burst or bad Oring down stream. The pressurized filter may still cause the hose to whip a bit in the case of a failed fitting but usually when that happens, it is the fault of the user using underrated or non compatible fittings or just failing to couple them properly. Those Zimkyfa fittings are well-made stainless and strong. I have had no trouble with them and the valves are very basic and function perfectly. They also cost next to nothing. If you were to buy the same thing from Joe Bandito, I guess you would pay more than 10 times what I paid. Before you buy elbows and other odd fittings, make sure that they are rated for the pressure that you are making. Always check that the direction the valve flows and that you have a bleeder, upstream, before pressurizing or you might find that you can't depressurize or uncouple anything without dismantling something.

 

[steve-l]

There is also a need by some, like myself, to use a male quick connect where the air flow is out not in. When I configured by Bauer compressor, I machined an output connector block that connects the pressure control switch, a pressure gauge, the inlet line from the final compressor stage and a male Foster fitting that can quick connect to the same whip used on my gun fill bottles. This allows me to fill the large bottles that I use to fill guns. However, the check valve in the Foster fitting must be removed first. This is easily done by using a pin punch from the quick connect side and a few light taps of a hammer. This does no damage to the check valve if you wish to reuse the fitting for its original purpose.

 

[steve-l]

One other thing. Please understand the difference between 1/8" BSPP and 1/8" NPT threads. These Foster fittings come in both BSPP and NPT threads. NPT threads seal on the threads and BSPP seal via a base washer not the threads. Do not confuse this.

 

[Bigragu]

One other thing. Please understand the difference between 1/8" BSPP and 1/8" NPT threads. These Foster fittings come in both BSPP and NPT threads. NPT threads seal on the threads and BSPP seal via a base washer not the threads. Do not confuse this.

I realize that. Trying to find a 90 degree elbow in BSPP female and male is hard to source, for what I’m looking for. I’ve settled on one I found at Amazon, made in SS and only comes in NPT. So, any fittings attached to that elbow is NPT.

so confusing, these British threads. I saw one the other day, and it’s being called out as BSPT. What is that!? The thing about fittings, if you order the wrong ones, your pretty much stuck with them unless you buy it local, cause shipping back for returns is on your dime. That’s another reason I stick with NPT. I would rather use BSSP cause I find the seal more forgiving and easy to change out if need be. The npt ones I’m always concerned about “stretching” out the female “hub” of the fitting when you first assemble them. But, npt fittings are easier to order and you know what your getting.

 

[Eaglebeak]

One other thing. Please understand the difference between 1/8" BSPP and 1/8" NPT threads. These Foster fittings come in both BSPP and NPT threads. NPT threads seal on the threads and BSPP seal via a base washer not the threads. Do not confuse this.

I realize that. Trying to find a 90 degree elbow in BSPP female and male is hard to source, for what I’m looking for. I’ve settled on one I found at Amazon, made in SS and only comes in NPT. So, any fittings attached to that elbow is NPT.

so confusing, these British threads. I saw one the other day, and it’s being called out as BSPT. What is that!? The thing about fittings, if you order the wrong ones, your pretty much stuck with them unless you buy it local, cause shipping back for returns is on your dime. That’s another reason I stick with NPT. I would rather use BSSP cause I find the seal more forgiving and easy to change out if need be. The npt ones I’m always concerned about “stretching” out the female “hub” of the fitting when you first assemble them. But, npt fittings are easier to order and you know what your getting.

BSPP has parallel sided threads. NPT and BSPT are tapered. When I need to convert NPT to BSPP, I run a BSPP die over the existing NPT or M10x1 thread. Some times it is just easier to modify a fitting than to find an adaptor or the correct premade one.

 

[Bigragu]

Wow! Good tip Eaglebeak! This is what I’m talking about, the nuts and bolts of the PCP hobby!

 

[steve-l]

One other thing. Please understand the difference between 1/8" BSPP and 1/8" NPT threads. These Foster fittings come in both BSPP and NPT threads. NPT threads seal on the threads and BSPP seal via a base washer not the threads. Do not confuse this.

I realize that. Trying to find a 90 degree elbow in BSPP female and male is hard to source, for what I’m looking for. I’ve settled on one I found at Amazon, made in SS and only comes in NPT. So, any fittings attached to that elbow is NPT.

so confusing, these British threads. I saw one the other day, and it’s being called out as BSPT. What is that!? The thing about fittings, if you order the wrong ones, your pretty much stuck with them unless you buy it local, cause shipping back for returns is on your dime. That’s another reason I stick with NPT. I would rather use BSSP cause I find the seal more forgiving and easy to change out if need be. The npt ones I’m always concerned about “stretching” out the female “hub” of the fitting when you first assemble them. But, npt fittings are easier to order and you know what your getting.

BSPP has parallel sided threads. NPT and BSPT are tapered. When I need to convert NPT to BSPP, I run a BSPP die over the existing NPT or M10x1 thread. Some times it is just easier to modify a fitting than to find an adaptor or the correct premade one.

There is a very big difference between the British standard and the American National standard beside just the pitch and taper and that is the thread form. The British threads use a 55 degree form and the rest of the world uses a 60 degree form. So no, running a 60 degree thread die over a 55 degree thread is a really bad idea. See below for definitions:

BSPP = British Standard Pipe Parallel, BSPT = British Standard Pipe Tapered, NPS, National Pipe Straight, NPT National Pipe Tapered.

Pipe size is based roughly on the ID of the pipe. Tubing is based on the OD. Wall thickness in pipe is specified by its schedule. Wall thickness in tubing is expressed by its wall thickness. The actual taper of tapered threads in both the British standard and the National standard is 3/4" per foot.

So, to make a hole for a NPT or BSPT tap is easy, just use the correct drill size. This is not so for straight threads because the bottom of the hole must be faced at a 90 degree angle for the BSPP seal and in the case of NPS, the top of the hole must be faced for the flange seal. Special tooling is required.

Straight thread seals should not be plastic of any kind as it creeps and easily deforms and not just because of over tightening. Fiber and soft copper or aluminum is best. There are steel ringed rubber seals available, which also work well often seen in hydraulics.

You will often see threads specified as "G" threads. These are NPS threads commonly used in the gas industry.

In conclusion, there are many thread standards out there in use today and they can be very confusing. They are NOT interchangeable. To make these threads takes a large very expensive investment in tools. It is very important to correctly identify a thread before trying to use it. Male threads can be identified with a caliper and thread gauges These are inexpensive tools and should be in everybody's tool box. This is not so easy for female threads .because the pitch and diameter can be the same between the British and National standards.

 

[Bigragu]

Steve, thanks for helping to take the mystery out of what all these fittings mean. Sounds like you’re in this line of work, pipe threads, fittings, etc. I never knew the T in NPT stood for Tapered. Good stuff, man.

 

[steve-l]

Steve, thanks for helping to take the mystery out of what all these fittings mean. Sounds like you’re in this line of work, pipe threads, fittings, etc. I never knew the T in NPT stood for Tapered. Good stuff, man.

I'm not actually. I am a retired IT professional, but I have also owned machine shops my entire life. I still own my own shop I have 3 lathes. The largest weighs 9.5 tonnes. I have 3 milling machines, shapers grinders, welders and plasma cutters. I have all these Taps&Dies for all these thread families, so I know how much these things cost. My input to this thread is really just an introduction to the subject. The history of threads is actually fascinating. All of this info is on the web and can be researched if you so desire. What you don't find on the web is the general uses of what and by whom in what industry. This is very useful in identifying female threads.because you often have to make a wag and then verify.

 

[BlackICE]

It would be difficult to tell the difference between 1/8 female BSPP and NPS that a lot of air guns seem to use for a gauge fitting. The difference being only 55 vs. 60 degrees.

 

[steve-l]

It would be difficult to tell the difference between 1/8 female BSPP and NPS that a lot of air guns seem to use for a gauge fitting. The difference being only 55 vs. 60 degrees.

You are partially correct, but there is also in the 1/8 size a pitch difference as well 27 verses 28 TPI.. It appears though that NPS threads are not generally used in the high pressure industry. With the exception of some American scuba gas bottles. The BSPP standard seems to be the thread family of choice. for compressors and fittings. You will find that the newer bottles are using the Metric thread standards like M18x1.0mm. This is done quite on purpose because the Scuba bottles that use the G3/4 NPS thread are only rated for 200 bar. You will find that NPS threads are common in Europe for low pressure air (8 to 10 bar) fittings where as the same application in the US is filled by NPT fittings.