For those of you who have hand pumps that you think have actually failed due to overheating. How hot do you think you got it before it actually went bad?
For those of you who have hand pumps and actually had them fail..
- Thread starter Healthservices
- Start date
The O-ring most susceptible to overheating is the one on the innermost rod...the one referred to as the final stage O-ring. It is so far from the exterior that by the time you could feel any substantial temperature rise, the O-ring is already toast. The longstanding recommendation is to pump in 50 stroke sessions and allow 15-30 minutes for it to cool down. Outside of that, its longevity will depend very much on the quality and material of the O-ring, the surface finish of tube, and state of lubrication.
Upvote 0
I have fried several in a Hill pump over the years. I do not believe they got too hot during a single use, but deteriorated from much use over time. The thing that finally killed mine was a stripped thread that prevented me from accessing the final stage rod and o-ring (which had gone bad). If you can't change out that final o-ring, it's done for. I'm a 40-50 stroke, bleed and let cool off guy. The aluminum base would become warm once you were pushing close to 3000 PSI. The o-ring on that final stage was viton, which should be good to about 400 degrees F. No way it was getting that hot. But I replaced that seal about once per year over the seven years I had the thing. My WAG on internal temp would be somewhere around 120-150 degrees. But I could be way off there.
Upvote 0
suffice it to say your likely going to toast your pump before its time if you over-do it .. 10 thousand round yackoff sessions just nonstop refilling from almost empty amd then never breaking it down to lube and dry it and it wont last long .. just topping off a gun you use for pesting and still periodically lubing and taking care of it and it will last for years ... mine is like 14 years old and about 12 of those its all i used and never replaced an oring yet although i have a spare set .. needs to be dried though .. DONT let it sit any period of time without breaking it down .. learn how to do that, first time is the hardest ..
Upvote 0
FWIW my experience with Viton for the final stage O-ring is that it failed relatively soon due to abrasion loss, even when using a 90 durometer (harder compound wears less). Both polyurethane and Buna-N seemed to last longer, despite both having a poorer high temperature rating.
Hill uses an HNBR O-ring (hydrogenated Buna-N) which is a tougher form of Buna-N but it is hard to find in 90 durometer.
On paper at least, Disogrin polyurethane seems to hold promise. That’s what I used about a year and half ago when I rebuilt the two pumps I use heavily. Both have held up great so far. This type of material may simply be referred to as “cast urethane” in most places.
Hill uses an HNBR O-ring (hydrogenated Buna-N) which is a tougher form of Buna-N but it is hard to find in 90 durometer.
On paper at least, Disogrin polyurethane seems to hold promise. That’s what I used about a year and half ago when I rebuilt the two pumps I use heavily. Both have held up great so far. This type of material may simply be referred to as “cast urethane” in most places.
Upvote 0
Healthservices
I use the 40 pump-15 minute cool-down procedure, but still managed to blow O ring up towards handle, on solid metal rod., from inside of inner brass piston. The outer part of my pump got pretty hot to the touch. Watched two-part YouTube video from Topa Manufacturing Company, featuring Coby Leo, "How to Repair the 300bar 4500psi PCP Air Rifle Hand Pump." (4/22/20) After watching several times, took mine apart and found NO COOLANT! Cleaned all parts, lubricated, as shown, replaced all parts included in spare parts bag and used mineral oil for coolant. Pump works fine, and operates much cooler. Contacted seller, informed of manufacturing defect, they gave $10 credit.
WM
I use the 40 pump-15 minute cool-down procedure, but still managed to blow O ring up towards handle, on solid metal rod., from inside of inner brass piston. The outer part of my pump got pretty hot to the touch. Watched two-part YouTube video from Topa Manufacturing Company, featuring Coby Leo, "How to Repair the 300bar 4500psi PCP Air Rifle Hand Pump." (4/22/20) After watching several times, took mine apart and found NO COOLANT! Cleaned all parts, lubricated, as shown, replaced all parts included in spare parts bag and used mineral oil for coolant. Pump works fine, and operates much cooler. Contacted seller, informed of manufacturing defect, they gave $10 credit.
WM
Upvote 0
Silicone has about the same high temperature rating as Viton but it also has very poor abrasion and tear resistance. Not a good material for this application.
Upvote 0
That's interesting about that final stage seal in the Hill. I was pretty sure I read Viton, but I do stand corrected. Regardless, I think only needing to replace that seal once a year on average (sometimes even before failure because I had the thing apart anyway) is reasonable for the amount of work I put it to.
Upvote 0
So having lube for that final stage oring is a good thing right?
Just silicone or should we use something else?
Just silicone or should we use something else?
Upvote 0
Healthservices
There are a number of O rings involved and silicone oil is used for lubrication. If you haven't done so already, look at the video I mentioned above. In 16 minutes it shows complete breakdown, cleaning and rebuild. The final stage reminds me of a .30 caliber smooth bore barrel with cleaning rod inserted. The "cleaning rod" is solid steel with spacer and "o" ring at end. This rod, moving up and down in "barrel" provides high pressure and heat. The hand pump has a sealed cylinder, around this final stage, filled with coolant that draws heat from "barrel." I'd be very surprised if your questions aren't cleared up by video, if not, always glad to help.
WM
There are a number of O rings involved and silicone oil is used for lubrication. If you haven't done so already, look at the video I mentioned above. In 16 minutes it shows complete breakdown, cleaning and rebuild. The final stage reminds me of a .30 caliber smooth bore barrel with cleaning rod inserted. The "cleaning rod" is solid steel with spacer and "o" ring at end. This rod, moving up and down in "barrel" provides high pressure and heat. The hand pump has a sealed cylinder, around this final stage, filled with coolant that draws heat from "barrel." I'd be very surprised if your questions aren't cleared up by video, if not, always glad to help.
WM
Upvote 0
Agreed, silicone oil for the dynamic O-rings of a high pressure pump. Oil, not grease. 30W works well.
https://www.amazon.com/gp/product/B0006MZSRW
It is also sold as treadmill lubricant. Just read the description carefully to be sure whatever you get is silicone and silicone only. Most will be.
https://www.amazon.com/gp/product/B0006MZSRW
It is also sold as treadmill lubricant. Just read the description carefully to be sure whatever you get is silicone and silicone only. Most will be.
Upvote 0
Wm the coolant you said was missing out of your unit. Is it something that is sealed away from everything else? I have pulled the base off I believe on my other pump and then just pulled the inner most shaft and found it dirty with brass bits. No large amounts of liquid came out. Just maybe about 5 or 10 drops of oil. I cleaned off best i could and reassembled and added a couple drops of oil. It worked with no issues after that but i also bought two more cheaper pumps since i figured I would burn them up surely by now. I do put a drop of silicone oil every 4 to 5 fills but at the same time I don't stop for the unit to cool during my fills either. Most my fills are from 150 bar to 300 and a couple 150 to 250 but does not ever get over 100° f . However the other day because of the post about filling up the tank, i decided to try it. I started at 3800 and at about 4200 i could feel that it actually was getting warm. I measured it and it was about 104. This made me think about actually maybe burning the seal up as it probably has been about 5 fills since I oiled it. I think i should probably just slow down the pumping after about 4k when pumping a medium sized bottle if i am to try again. Also to to take a look and see if i could put some coolant as you said you did to yours.
Upvote 0
Wow i looked up silicone oil and had no idea there were so many weights available! I bought a bottle of the 30 weight. Thanks
Since the video mention just using automotive coolant and I have plenty of that, that is what I will use. Especially since coolant can conduct/draw out heat better than a light oil. I was just afraid it would add moisture to the compressed air. it appears to be in a totally separate and contained chamber.
Upvote 0
Healthservices
Thank you for watching video, much easier to discuss and understand. I don't recall Coby Leo ever mentioning "automotive" coolant, he just called it coolant. You are correct, when I tilted my pump to empty coolant into cup, like Coby Leo, nothing came out. NO COOLANT installed. You are also correct that the coolant system is a totally separate and contained chamber, not able to add moisture to compressed air. Antifreeze and mineral oil are both good replacements for coolant, but you can always re-use coolant. Like dizzums said, periodic breaking down, cleaning and lubing will help it last years. Not sure if you've had your pump apart yet, but watching Coby Leo's video a few times gave me confidence to go ahead. Now I laugh at my hesitancy, seems so easy now. As always, we're here to help,
WM
Thank you for watching video, much easier to discuss and understand. I don't recall Coby Leo ever mentioning "automotive" coolant, he just called it coolant. You are correct, when I tilted my pump to empty coolant into cup, like Coby Leo, nothing came out. NO COOLANT installed. You are also correct that the coolant system is a totally separate and contained chamber, not able to add moisture to compressed air. Antifreeze and mineral oil are both good replacements for coolant, but you can always re-use coolant. Like dizzums said, periodic breaking down, cleaning and lubing will help it last years. Not sure if you've had your pump apart yet, but watching Coby Leo's video a few times gave me confidence to go ahead. Now I laugh at my hesitancy, seems so easy now. As always, we're here to help,
WM
Upvote 0
It was under comments... not automotive but "car"
And my big thing was people's stand on how the pumps fail by overheating. I have a better understanding of it now. basically the way I understand it, many times it is the high pressure seal and it is when the seal deteriorates to the point it no longer seals. heat can contribute to it, but it can be from the lack of oil, dirt, or just wear.
Upvote 0
Healthservices
You sir, are correct. I've seen video many times but never read comments. I feel very confident you've got a good grasp of the PCP handpump. When I had mine apart I even ran silicone soaked cleaning patches down my "barrel" to get rid of that black gunk the Chinese use for lubricant. I then dripped a few drops of 30w silicone down nice clean "barrel" before following Coby's re-installation procedures. My handpump never worked better, and now, thanks to mineral oil, doesn't even get hot. I'm not sure what came in your spare parts bag but mine had extra plastic spacer and "o" ring for end of "cleaning " rod. I replaced, as I'd overheated my originals. I wish you nothing but smooth sailing ahead with your hand pumps,
WM
You sir, are correct. I've seen video many times but never read comments. I feel very confident you've got a good grasp of the PCP handpump. When I had mine apart I even ran silicone soaked cleaning patches down my "barrel" to get rid of that black gunk the Chinese use for lubricant. I then dripped a few drops of 30w silicone down nice clean "barrel" before following Coby's re-installation procedures. My handpump never worked better, and now, thanks to mineral oil, doesn't even get hot. I'm not sure what came in your spare parts bag but mine had extra plastic spacer and "o" ring for end of "cleaning " rod. I replaced, as I'd overheated my originals. I wish you nothing but smooth sailing ahead with your hand pumps,
WM
Upvote 0