[Rickys bong]

Originally Posted by Kenzyme

Are these bearings standard size to their part number, or are there different sizes for each part number? and if so what are the appropriate sizes?

The number is unique to each bearing size, and they are standard sizes. The letters at the end designate the type of seal they have.

RB

[Kenzyme]

Originally Posted by FishmanK

Saw a post by BHOgart in last few days that they have new bearing assemblies for these pumps with PTFE components
Asking about that yesterday @ BHOgart Eureka, was told that the San Jose store was the spot for rebuilds and new bearings for CMEP-OL

Called them yesterday and ordered the bearing set. I will report an update when installed with pics if I have time.

[Pure777Extracts]

Originally Posted by Kenzyme

Called them yesterday and ordered the bearing set. I will report an update when installed with pics if I have time.

Im pretty sure it is the bearings, That sounds like the sound mine was making when I took it in. BHOgart cleaned and lubricated bearings and was good to go. Going to get the new PTFE coated bearings later in the week.

[Old Gold]

I'm waiting for a call back hopefully, that they can also machine a hole in the crankcase. I didn't get to speak with the pump tech like I was told I would lol, but Sean at the San Jose store is looking into it for me. He's always been pretty helpful and upfront about things.

$100 for labor ain't bad. What are they charging for the bearings themselves?

Originally Posted by Rickys Bong

Ideally it should be plumbed to a line that can be vented outside or into an external tank.
Band aid solution would be to put a mol sieve between the compressor outlet and the heat exchanger or at lease on the heat exchanger / condenser outlet on the outside of the compressor.

How does molecular seive fix the issue? I don't follow.

[Rickys bong]

Originally Posted by Old Gold

How does molecular seive fix the issue? I don't follow.

Mol sieve on the outlet side will catch any grease exiting the commpressor.

RB

[n8oler]

I second RB, on the outlet for inevitable grease expulsion into your solvent tank from the CMEP-OL bearings(once the piston rings fail).
In my experiences pump failure/leakage is contributed to liquid solvent/extracts making their way from the collection vessel into the inlet of the pump. Which, creates buildup and ultimate top-end failure which lets solvent into the crankcase and decomposes the bearings seals.

[Old Gold]

Originally Posted by Rickys bong

Mol sieve on the outlet side will catch any grease exiting the commpressor.

RB

Right, I guess I should've been more clear...do we know what will effectively catch all residues from the pump?
I wouldn't think molecular seive would remove the need to fix up the crankcase.

[n8oler]

I know I'm a noob, but let me introduce myself. I have a year of testing and CMEP-OL rebuilds under my belt with a background in pharmaceutical engineering/fabrication. Which, has led me here to try and help the industry, most specifically CMEP's and sanitary fabrication.

OG to answer you questions

2 expansion chambers filled with 4a desiccant beads with a bottom -> up flow orientation on intake and exhaust will effectively catch all residuals and safeguard the pump.

A molecular sieve will remove the need to fix up the crankcase. (Though a bleeder valve on the bottom of the crankcase is not a bad idea!)
1. Every bearing has a lifespan and will fail at some point. Much quicker with solvent flushing the grease away from the ball bearings.
2. Solvent should not enter your crankcase at anytime. If it does you have piston ring failure.
3. If you have piston ring failure, its because you have extracts entering the pump. Its like throwing sand in the intake of your car.


I have been talking with Andrew at Sanitary Steel to provide feedback to CM refrigeration for the next generation.

These are my recommendations;

All compression fittings(no JIC refrigerant or npt fittings) Swagelok preferred.

All stainless(no brass on gauges, p-switch).

No brazing.

Better valves Swagelok preferred.

Better gauges Swagelok preferred.

Bearings that will not contaminate(100% sealed or ceramic).

Leak down test for the cylinders(indestructive way to test piston rings).

No radiator style condenser, something like a coil or jacketed (everyone has ice/dry ice/chillers).

Molecular sieves on both sides(expansion desiccant bead chamber).

Valved, vented crankcase with an oil catch basin.

Electrical box with nitrogen purging.

A step on the shaft to set crank depth/piston alignment on the shaft.

LMK if you have more questions!

[Rickys bong]

Originally Posted by n8oler

A molecular sieve will remove the need to fix up the crankcase. (Though a bleeder valve on the bottom of the crankcase is not a bad idea!)
1. Every bearing has a lifespan and will fail at some point. Much quicker with solvent flushing the grease away from the ball bearings.
2. Solvent should not enter your crankcase at anytime. If it does you have piston ring failure.
3. If you have piston ring failure, its because you have extracts entering the pump. Its like throwing sand in the intake of your car.

The piston seal they used is going to let a small amount of gas into the crankcase even when they are new. That's why I suggested a vented crankcase is the only way to solve the issue with some degree of certainty. I've seen this issue with other pump designs as well. Some designs pressurize the crankcase to balance the pressure across the piston seal but that concept allows crankcase contaminants to get into the pump outlet circuit.

What I'm sure is happening is that gaseous butane is dissolving into the bearing grease which comes out of solution when the pump is off and the pressure drops. Depending on conditions, when the butane starts boiling out of the grease it can push the grease past the seals.
I've seen this happen with the various pumps I've tried over the years. Eventually enough gets out to splatter onto the cylinder walls where it will find its way back to the top of the piston and the fluid being compressed. Not good.

Especially with the CM pump, the piston seals do a poor job of sealing anything that wants to go from the bottom of the piston upwards. Horrible design and only a single seal.
If the crankcase is vented through a tube that can be vented outside butane can never dissolve into the grease. You can also monitor any flow from the crankcase vent to monitor the health of the seals.

It's a conceptual design issue that better bearing seals won't solve. Their larger compressor is the same design, just 4 pistons instead of 2.

Peace

RB