Lane fill probe leaking

[Iowa Airgunner]

I have noticed over the last few months that my Air Arms HFT 500 leaks sorta.

The air tube is a 300cc tube from air Venturi and I have a Lane regulator inside the tube. So the gauge on the bottom of the gun only reads regulator pressure. On the front of the tube the Air Arms Fill adapter has been replaced with a Lane fill probe and gauge.

Quickfill & Gauge Unit..pdf

drive.google.com

If I fill the gun to 3000 psi it will leak down to 2800 and hold that pressure for weeks. Until last week. It would suddenly lose Al lot of pressure mysteriously.

So now that I got the scope all dialed in and it is shooting so perfectly. I decided to look for the leak. I covered the barrel with a surgical glove finger tip and tape. I put silicone in the vent for the regulator and at the last minute I put the fill probe in with some silicone blocking the hole. As soon as I put the probe in the silicone popped out.
The leak is from the inside the fill probe.
I pulled the fill probe and found some crap. But the O ring has a tiny divot from the hole in the metal that allows air to pass. Somehow the O ring turned and it leaks. And after looking at it it leaked bad. I can’t use the original fill because I can’t see the pressure.
I fortunately found a 9x2mm O ring with a 4mm center. It is fractions of a millimeter larger than the original. But it worked. I tried a couple others and they did not.
Let’s see if it holds while I look for a regulator rebuild kit or order O rings from Mc master Carr.

 

[rdtricks]

If you know the size of O-ring need to fix the leak you might try ordering from one of these two vendors. I have found them to be less expensive that McMaster-Carr and very responsive:
1) https://www.oringsandmore.com
2) https://www.theoringstore.com/store/

There are other O-ring vendors like Amazon and Ebay also.

 

[Iowa Airgunner]

I have Mc master carr
The O ring is distorted. But in metric it is OD 9mm Width 2mm inside 5mm.
In fractional size its OD is 5/16 width is 1/16 and inside is 3/16.
Fractions its OD.350 width .075 and ID is .175.
I found a couple that are very close and a box of fifty for five dollars. Shipping is 15 bucks so I might as well order a couple different sizes. I’m not sure about the hardness number.

It is still leaking. I filled it up and hope the O ring might form some sort of seal over night. I might have to put a plug in the fill probe if I can’t get it to seal.

 

[Iowa Airgunner]

After looking at the different options I decided to replace the whole fill probe gauge adapter.

Air Arms Quick Fill Conversion Kit for S3/4/510 EV2, FTP900 & ProTarget

Upgrade your standard Air Arms cylinder fill port to a Gauge and Quickfill unit, allowing for a front-mounted gauge allowing a fill reading once regulated. The built-in gauge and rotating collar ensure convenience and protection against dust and dirt. The kit includes the fill probe, featuring a...

www.apexairguns.com

Kind of an over kill approach . But I gotta fix it. And the next comp is in a month.

 

[Iowa Airgunner]

I hooked up the hose to my compressor and after an hour it put a 1000 psi into the compressor gauge. Definitely leaking from the fill probe. So I put a plug in the hose and I’ll just store it like that till I get new parts.
This gun has a lot of pellets through it. But it shoots so well . I just need to work on the seals a little.

 

[Iowa Airgunner]

I spent a lot of time with better measuring devices and methods and ordered a 15 dollar box of O rings. I am going to keep trying to fix the Lane regulator. But with lane out of business I guess I need to get something else.

Anyone know how a Regulated S500 gauge works? My regulator is in the tube the gauge under the stock reads regulated pressure. The gauge on the fill probe reads tank pressure.

I only see one gauge on an S500.

 

[Iowa Airgunner]

I spent some time looking at how this seal system seems to work. There are two holes in fill probe body. One small port on the edge that goes from the tank to the gauge. The other is a central hole that is tapped and goes from the fill port to the tank. A tapered screw is threaded into the center and compresses an O ring between the taper of the screw and the body of the gauge block. Air travels up a slot cut into the screw and can push the o ring out . But when there is pressure in the tank the o ring gets squeezed and seals.
Unless there is a cut into the screw !
I found this scratch from when they cut the slot for the air.
I rebuilt it all with a new screw. I cut the slot with a diamond burr.

 

[Iowa Airgunner]

Still holding tight two hours later. Last night could hear it leak . And the best it has been is a tiny leak from the fill port. I am shocked it was something like this. I am not unhappy about buying a new probe adapter. Having a back up is great when you travel to a competition.

 

[Iowa Airgunner]

24 hours and the rifle is holding 2800 psi. Exactly like it was yesterday. I can’t believe it!!!

So after thinking about this all night.
Someone at Lane was cutting the air slot in the screws and cut the tapered seal surface. When assembled new it was probably fine. But after a couple years this persistent leak developed. Not a full leak but a slight leak. Like a pressure regulator and the gun would only hold 2500 psi no mater how much air you put in.
Now it is holding 2800psi. It was getting about 60 shots per fill and I only shoot fifty before I refill. So 2500 down to 1200-1500 is 60 shots. Regulator is set to 1000 psi. If I fill to 2800 I might get 84 shots from one fill. That would be a full practice session without a refill. And a comfortable 72 shots for the competition.