MCH6/EM tweaking to 232 bar

gallathan · 2nd March 2008, 09:00

I have a new MCH6/EM compressor, that runs fine, but consistently cuts out between 185 and 190 bar. I'm filling steel 232 bar din 3 ltr cylinders, and would like to get a fill in the range of 232 to 250 bar. I am water cooling the cylinder, and using a digital spg, which I've calibrated prior to filling. I've also double checked the pressure using an ordinary pressure guage, so I'm sure this is the pressure I'm getting. Any ideas why / how to adjust the shutoff/pressure valves on an MCH6/EM?

mattarte · 3rd March 2008, 13:08

Quote: (Originally Posted by gallathan)

I have a new MCH6/EM compressor, that runs fine, but consistently cuts out between 185 and 190 bar. I'm filling steel 232 bar din 3 ltr cylinders, and would like to get a fill in the range of 232 to 250 bar. I am water cooling the cylinder, and using a digital spg, which I've calibrated prior to filling. I've also double checked the pressure using an ordinary pressure guage, so I'm sure this is the pressure I'm getting. Any ideas why / how to adjust the shutoff/pressure valves on an MCH6/EM?

Just use a wrench and turn the OPV till you reach the desired pressure

gallathan · 3rd March 2008, 20:45

Thanks for the reply, staring at parts diagram in manual now. Safety valve sure looks like an OPV, with a hex style fitting, presume thats what you mean, will tighten it up, and refill cylinder. Found out if I used PTFE tape on the fittings (have added personal filter and digital spg), that got rid of a few leaks, so I got to 200 bar before safety valve cut out. Manual states 250 bar max, I suspect in real life, may get a bit less, maybe 245 bar, heres hoping ;-). Have you tried this on an MCH6/EM, what pressure did you manage to achieve?

mattarte · 4th March 2008, 06:48

Quote: (Originally Posted by gallathan)

Thanks for the reply, staring at parts diagram in manual now. Safety valve sure looks like an OPV, with a hex style fitting, presume thats what you mean, will tighten it up, and refill cylinder. Found out if I used PTFE tape on the fittings (have added personal filter and digital spg), that got rid of a few leaks, so I got to 200 bar before safety valve cut out. Manual states 250 bar max, I suspect in real life, may get a bit less, maybe 245 bar, heres hoping ;-). Have you tried this on an MCH6/EM, what pressure did you manage to achieve?

No problem in reaching 250 bar (also more) but since i'm doing mostly continuous mixing with an average content of 50% of Helium, i prefer to stop at 225. My MCH6 is a 1998 model (so may be there are some differences with yours). I bought it second hand in 2001. I changed the pistons sealings immediately and since then is working fine. Hope you'll have the same satisfaction with it.

mattarte · 4th March 2008, 06:56

Quote: (Originally Posted by gallathan)

Safety valve sure looks like an OPV, with a hex style fitting, presume thats what you mean

Mine looks exactly like this Salvo Diving Equipment - OPRV

***Beanie*** · 4th March 2008, 07:24

Quote: (Originally Posted by mattarte)

Mine looks exactly like this Salvo Diving Equipment - OPRV

I hope its not one of them :P
If it's the same style but higher pressure they'll be a nut inside to adjust the top hex is a cap under that is the adjustment.

Might be worth noting that the MCH6 has a pressure maintaining valve and a pressure relief valve. Make sure you get the right one else you'll end up with a compressor that doesn't fill. If the OPV is lower than the PMV.

It might be worth seeing if you can get hold of Barrie Law, he's should be the best person to ask. Might be a bit busy at the mo though.

mattarte · 4th March 2008, 07:43

Quote: (Originally Posted by Beanie)

I hope its not one of them :P
If it's the same style but higher pressure they'll be a nut inside to adjust the top hex is a cap under that is the adjustment.

Don't worry, it was only to show the shape of the component

2nd March 2008, 09:00	#1 (permalink)
gallathan still learning... Current Rebreather/s: Inspiration Classic Inspiration Vision Other Rebreather/s: Join Date: Mar 2006 Location: Laleham, Middlesex, England, UK Posts: 63	MCH6/EM tweaking to 232 bar I have a new MCH6/EM compressor, that runs fine, but consistently cuts out between 185 and 190 bar. I'm filling steel 232 bar din 3 ltr cylinders, and would like to get a fill in the range of 232 to 250 bar. I am water cooling the cylinder, and using a digital spg, which I've calibrated prior to filling. I've also double checked the pressure using an ordinary pressure guage, so I'm sure this is the pressure I'm getting. Any ideas why / how to adjust the shutoff/pressure valves on an MCH6/EM?
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3rd March 2008, 13:08	#2 (permalink)
mattarte New Member Current Rebreather/s: Not Bought Yet Other Rebreather/s: Not Bought Yet Join Date: Aug 2006 Location: Segrate Posts: 15	Re: MCH6/EM tweaking to 232 bar Quote: (Originally Posted by gallathan) I have a new MCH6/EM compressor, that runs fine, but consistently cuts out between 185 and 190 bar. I'm filling steel 232 bar din 3 ltr cylinders, and would like to get a fill in the range of 232 to 250 bar. I am water cooling the cylinder, and using a digital spg, which I've calibrated prior to filling. I've also double checked the pressure using an ordinary pressure guage, so I'm sure this is the pressure I'm getting. Any ideas why / how to adjust the shutoff/pressure valves on an MCH6/EM? Just use a wrench and turn the OPV till you reach the desired pressure
(Offline)

3rd March 2008, 20:45	#3 (permalink)
gallathan still learning... Current Rebreather/s: Inspiration Classic Inspiration Vision Other Rebreather/s: Join Date: Mar 2006 Location: Laleham, Middlesex, England, UK Posts: 63	Re: MCH6/EM tweaking to 232 bar Thanks for the reply, staring at parts diagram in manual now. Safety valve sure looks like an OPV, with a hex style fitting, presume thats what you mean, will tighten it up, and refill cylinder. Found out if I used PTFE tape on the fittings (have added personal filter and digital spg), that got rid of a few leaks, so I got to 200 bar before safety valve cut out. Manual states 250 bar max, I suspect in real life, may get a bit less, maybe 245 bar, heres hoping ;-). Have you tried this on an MCH6/EM, what pressure did you manage to achieve?
(Offline)

4th March 2008, 06:48	#4 (permalink)
mattarte New Member Current Rebreather/s: Not Bought Yet Other Rebreather/s: Not Bought Yet Join Date: Aug 2006 Location: Segrate Posts: 15	Re: MCH6/EM tweaking to 232 bar Quote: (Originally Posted by gallathan) Thanks for the reply, staring at parts diagram in manual now. Safety valve sure looks like an OPV, with a hex style fitting, presume thats what you mean, will tighten it up, and refill cylinder. Found out if I used PTFE tape on the fittings (have added personal filter and digital spg), that got rid of a few leaks, so I got to 200 bar before safety valve cut out. Manual states 250 bar max, I suspect in real life, may get a bit less, maybe 245 bar, heres hoping ;-). Have you tried this on an MCH6/EM, what pressure did you manage to achieve? No problem in reaching 250 bar (also more) but since i'm doing mostly continuous mixing with an average content of 50% of Helium, i prefer to stop at 225. My MCH6 is a 1998 model (so may be there are some differences with yours). I bought it second hand in 2001. I changed the pistons sealings immediately and since then is working fine. Hope you'll have the same satisfaction with it.
(Offline)

4th March 2008, 06:56	#5 (permalink)
mattarte New Member Current Rebreather/s: Not Bought Yet Other Rebreather/s: Not Bought Yet Join Date: Aug 2006 Location: Segrate Posts: 15	Re: MCH6/EM tweaking to 232 bar Quote: (Originally Posted by gallathan) Safety valve sure looks like an OPV, with a hex style fitting, presume thats what you mean Mine looks exactly like this Salvo Diving Equipment - OPRV
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4th March 2008, 07:24	#6 (permalink)
*Beanie* give a man an inch....... Current Rebreather/s: Inspiration Classic Other Rebreather/s: Inspiration Vision Join Date: Jan 2005 Location: In da house! yeah baby! Posts: 3,174	Re: MCH6/EM tweaking to 232 bar Quote: (Originally Posted by mattarte) Mine looks exactly like this Salvo Diving Equipment - OPRV I hope its not one of them :P If it's the same style but higher pressure they'll be a nut inside to adjust the top hex is a cap under that is the adjustment. Might be worth noting that the MCH6 has a pressure maintaining valve and a pressure relief valve. Make sure you get the right one else you'll end up with a compressor that doesn't fill. If the OPV is lower than the PMV. It might be worth seeing if you can get hold of Barrie Law, he's should be the best person to ask. Might be a bit busy at the mo though. __________________ Beanie Gallery Admin & Library Assistant. www.outlawdivers.org.uk www.beandiving.co.uk www.beanengineering.co.uk
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4th March 2008, 07:43	#7 (permalink)
mattarte New Member Current Rebreather/s: Not Bought Yet Other Rebreather/s: Not Bought Yet Join Date: Aug 2006 Location: Segrate Posts: 15	Re: MCH6/EM tweaking to 232 bar Quote: (Originally Posted by Beanie) I hope its not one of them :P If it's the same style but higher pressure they'll be a nut inside to adjust the top hex is a cap under that is the adjustment. Don't worry, it was only to show the shape of the component
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