Description
PCP High Pressure Compressor by Mark IV.
The PCP High Pressure Compressor that Gunroom markets under the Mark IV brand, comes as a dedicated PCP air rifle filling station. There are quite a few marked differences between the Yong Heng compressor as you buy them and this PCP high pressure compressor.
Those of you who have purchased one of the Yong Heng compressors from the Internet, would instantly see a few short-comings as they are supplied. With at least 7 variations of the same compressor, they range from terrible up to quite good in feed-back.
Essentially the compressors are much the same with some having fewer air pipes, plug in water pipes (that continue to leak or drop out when warm…), poorly secured internals etc. I know this because we have purchased various units to try them out and we also get quite a few in for repairs. This is what prompted us to talk to the manufacturer and get a custom built PCP high pressure compressor that suits our industry, and so after placing an order for 100 units (minimum size order), we can now supply out of our own stock.
PCP High Pressure Compressor Cooling.
Our PCP high pressure compressor requires a cooling medium to which you fit a small water pump (supplied) with silicone hose to the compressor and a return feed back to the tank. I find that a cooling tank of 30 litres will control the compressor temperature better than a smaller tank.
The paperwork says that the pump should not exceed 70 degrees, however, in my humble experience over a couple of years with these compressors, I seldom exceed 60 degrees and if I do exceed that, I NEVER go over 65 degrees.
One of the issues here is that the temperature gauge on the housing, shows the temperature of the PCP high pressure compressor and not the electric motor driving it. I have seen blistered starting capacitors on compressors that have never exceed 60 degrees and this has led to us modifying the electric motor part of these PCP high pressure compressor units.

Modifying a PCP high pressure compressor
Filling a SCUBA bottle with a PCP high pressure compressor by Mark IV.
The temptation for some is to connect this little PCP high pressure compressor to a large Scuba tank and leave it to do its’ stuff. So here is a tip for you, I do NOT recommend running the compressor for more than 20 minutes at a time. While the compressor may be running cool and under 60 degrees, I can tell you now that the electric motor is hotter than that. I reckon you can run the compressor for 20 minutes and let it cooling for 40, then rinse and repeat. Those of you in cooler climes can most likely run the compressor longer.
Our PCP high pressure compressor is 2 years old and has never missed a beat, it has filled literally hundreds of PCP air rifles and our 300 bar reserve tank too. I generally switch the compressor over to our 300 Bar Scuba tank after filling a PCP air rifle, and let it run for 15 minutes more. Over the course of a few air rifle fills, the Scuba bottle gets filled too.
The Mark IV PCP high pressure compressor is not bullet-proof and certainly not idiot proof either. I you are the sort of guy who looks after his gear, then this little compressor will look after you with the minimum of service required.
I suggest that you never leave the compressor while it is running, because sure as sh*t something will come adrift or go wrong. I have heard of the silicone hoses popping off when the pump is running: after a little bit of research found out on 2 occasions that the owners had used oil on the hose ends to ease pushing them onto the brass barbs…duh?
Do NOT use oil on the silicone hoses guys: if the hoses are a bit tight to push on the brass barbs, use some saliva rather than oil, it works OK in the bedroom and I know it works here too. The Mark IV PCP high pressure compressors supplied by us come with “pre-attached” silicone hoses that are less prone to kinking and have a better life expectancy that that crappy clear pvc hose. You will also notice I use cable ties on the silicone hose ends.
Summarising the PCP high Pressure compressor.
With filling times running at around 40 seconds to refill a Brocock Compatto through to 2 minutes for a Daystate, this PCP high pressure compressor is invaluable for the avid air gunner. You will also notice that many PCP air rifles have a restrictor in line with the air cylinder, this is there to stop the air tank being filled too quickly. However, what does happen is that the air flowing through the restrictor gets very hot, in so doing it heats up the air cylinder as well.
This hot air will cool down and in doing so it will lower the final air cylinder pressure. To compensate for this pressure reduction I over-fill the air cylinder by 10% as it generally cools down and lands around the correct fill pressure.
One last thing I need to mention and that is you must dump the air quickly when you are ready to remove the filling line. This helps seat the air valve and helps to prevent the slow leaks that sometime are associated with PCPs. As for the filter, with the Mark IV PCP high pressure compressor we use a larger filter that has carbon in it as well as the water absorbing pellets.

Large PCP High Pressure compressor filter
You need to leave the valves OPEN when the compressor is not in use, this will allow any moisture present to dry out. Store the large air filter upright and above the high pressure compressor to allow moisture to run back down and out when not in use. You must also periodically check the filter element and dry it out or replace it. You need to read more about the servicing of your PCP high pressure compressor on this link.
Author
Ian McIntosh