Coupling for Reciprocating Compressor

[wzal]

Hi,

I am designing a direct drive system including an electric motor and a 6 -cylinder reciprocating compressor.

How much is the service factor I should use when I size the key and coupling hub/spider (because of the vibration)?

Thanks,

 

[pennpoint]

wzal
This seems to be an odd question to me because all the open compressor/motor interfaces I have done (50 to 100hp). The motor/compressor shafts are already machined for a key.
You need to match each (if each is diffrent)with the correct coupling with the correct keyway.
In addition, I would recommend that you choose a flexible plate coupling instead of a spider type. Alignment of the motor/compressor is very, very critical. A spider type is not up to that task.
Contact the compressor manufacture for motor/compressor coupling guidlines, Iam sure they will be glad to help you.

Best Regards

pennpoint

 

[HVAC68]

Absolutely right - With an open type compressor, one of the biggest problems faced is a shaft seal leak due to mis-alignment. Get this done correctly and the compressor (generally) is a workhorse and doesn't pose too many problems.

HVAC68

 

[quark]

If Pennpoint means bush and pin type coupling by flexible plate coupling, then I also suggest tyre coupling as an alternative.

 

[imok2]

A Thomas coupling has always been the perfect choice for me
Look here:

http://www.couplingcorp.com/

 

[pennpoint]

quark

The type of coupling I meant is shown in the attached.

http://www.rinomechanical.com/couplings/high-torque-flex.pdf

This type does not tolorate much missalignment therefore the motor/compressor alignment is critical. A tire (tyre) or elastomeric type you suggest dismisses the the critical alignment because they have a large compensation factor. Misleading the installer into a false sence of "thats GOOD ENOUGH". The seals on an open style refrigeration compressor cannot tolorate "ANY" side load.
I have to admit that its been awhile since I have done one of these, but I would still use dial indicators, alignment V-blocks and get it done right.
I strongly recommend that the compressor manufacture be consulted. If this were a Carlyle Compressor I know they have accepted procedures and approved couplings.
BTW stating that the compressor has six cylinders means nothing, it could be a 25hp or up to a 120hp compressor. These compressors are brutes and worth the big $$$ they get for them. Do a good job of installing them and you'll get long time service from them without expensive refrigerant loss and warranty service calls.

All this is only my opinion.

Best Regards
pennpoint

 

[wzal]

Thank you all for your valuable input.
I have a Lovejoy Jaw type and a Rex Omega coupling. Both of them have torque capacity 4 times of continuous torque of the application. But both of the 2 coupling manufacturers didn't say how much is the service factor I should use on the spec. (it seems to me recip compressor system is special application for these guys cause I can find service factor for all sorts of other applications).
Does anyone use any of the 2 types of coupling on recip compressor?

Regards,

 

[krb]

Has anyone ever used a Falk coupling in this same service?

krb