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DHARMENDRA1985
11-12-2016, 07:05 PM
Hi Guys...
I m new to this forum, need help you in certain areas.
I m making R404a system first time so not sure about the good system operating pressures.
Like my system is for -20 product temperature and i m getting 300 psi at dis and 10 psi at suction with -28 deg evaporating temperature...is it good or stable . Pls comments

mikeref
12-12-2016, 07:42 AM
10 PSI Suction is less than the required pressure for a R404a Display Freezer. Superheat will be high so you will have a starved Evaporator and a compressor running hot. For -20 C, you should have around 22 PSI and a Superheat of 7 Degrees C or K.
300 PSI discharge with a 10 PSI Suction sounds like your Condenser is undersized.

DHARMENDRA1985
12-12-2016, 07:17 PM
Thanks for Ur reply.
What's the safety limit for discharge pressure to safe running of compressor..I m getting 44 deg liquid temp at 32 deg C ambient..
Discharge pressure mentioned above.
Can it trip the compressor in high ambient conditions.

mikeref
13-12-2016, 07:57 AM
You are not going to have an efficient system when your Discharge is beyond 300PSI. Raising Suction pressure will limit heat rejection at the Condenser. Liquid temp at 44 C on a 32 degrees C Ambient shows your condenser is far too small.