Refrigeration 101

[mad fridgie]

Originally Posted by ianparker0801

Thanks for you help gary, it all helps when trying to apply the theory to practical application. My next question is about high pressure and low pressure cut outs. How do you go about testing these safety features, on both courses we were told to check these but noone has ever said how.

Pressure switches can be tested with a nitrogen via a regulator/gauge, Raise pressure until switch changes. make a note of actual pressure, then slowly release until switch changes back. Adjust until you reach desired set points. "Note" the scale are indicators only, for rough adjustment.
On site, you sort of break a few rules, for HP (discharge) you "slowly" close discharge valve, keeping a very close eye on your gauge. Hp switch will trip (at some set point). (if manual reset then no other settings to check) if auto reset then watch as the pressure drops note switch change, for LP similar process but switch is is opposite direction

[goshen]

hi garry very nice thread should answer a lot of newbies questions!!!

[Gary]

Don't forget to click the reputation button.

[Uni]

It's really useful, Garry. After 1 year of self-learning, you give me have a chance to review what I have been done and believe were right or not.

Can you write something about system balancing (using captube) and how to get the max cooling capacity out of the component we have? Or say how to tune a unit?

How the excessive Cond airflow and/or Evap airflow can bring the Capacity down? It looks like I have more SC, lower HP, so I can add more charge to control SH after drawing the Capacity line against charge amount. But it made no sense as I did not get what I had.

Capacity has always been a problem of mine since I started playing

Thanks, Gary

[Gary]

Insufficient (not excessive) airflow brings down capacity.

[shaafeq]

In Freezer with capilary as metering devices, how to determine if the system is overcharged or less charged with a refirgerant? Can we decide this base on the suction line temp., discharge line temp./ before filter dryer temp.?

[shaafeq]

Hi Gary,

I've a question for you. In Freezer system, how we can determine whether the system is overcharged or less charged base on the suction line temperature (evaporator in / out), accumulator out temperature, before filter dryer temperature, discharge line temperature? Let say the system is unsing capilalry as the metering device. Hope you can give me some hints regarding this.

[nike123]

Originally Posted by shaafeq

In Freezer with capilary as metering devices, how to determine if the system is overcharged or less charged with a refirgerant? Can we decide this base on the suction line temp., discharge line temp./ before filter dryer temp.?

Before/or filter dryer temperature will tell the difference.


In a system that is short of refrigerant the condenser would have a gradual change in temperature from the top all the way down to the strainer. In fact the strainer will be slightly above room temperature.

In a system that is overcharged strainer will be at same tamperature as lower part off condenser.

http://www.supco.com/images/pdfs/Man...g%20Manual.pdf

[Gary]

Most accurate would be to weigh in the charge.

[Gurdev Singh]

Hi All
I have one question recently I worked with vendor of FES Screw Chiller with 20,000kg of R 134a ref charged and 800 gallon of Lubricnt oil . Now i am envolved in commissioning of another chiller it has a Propane gas charging can some body tell me what will be the running parameters with Propane Refrigerant

[nike123]

Originally Posted by Gurdev Singh

Hi All
I have one question recently I worked with vendor of FES Screw Chiller with 20,000kg of R 134a ref charged and 800 gallon of Lubricnt oil . Now i am envolved in commissioning of another chiller it has a Propane gas charging can some body tell me what will be the running parameters with Propane Refrigerant

Parameters will be same in temperatures as with R134a. Pressure will be saturation temperatures of Propane converted to pressures.