Compressor room ventilation requirements for compressor racks??

[buddy]

Hi Folks,

I have a 100 horsepower compressor rack fitted with 4 x Copeland 25 HP compressors operating on R22 refrigerant that is cooking in a sauna of a plant room/compressor room because there is no ventilation installed, its + 41 degrees Centigrade!

The customer is being cooperative and will install cross flow ventilation in the compressor room.

However he has asked me for the technical ventilation data so he can instruct the ducting company to install it and this has stumped me.

I have already asked Copeland what the minimum ventilation requirements are and I didn't get a satisfactory answer.

Question?

In my application described above would the minimum ventilation requirement be based on volume air changes per hour?, velocity per Compressor horsepower?, heat rejection of compressors?, what is the criteria??

Is there also a rule of thumb calculation that the ventilation industry uses for compressor racks/Compressor rooms or is it a more complicated calculation?

Your help would be most appreciated.

best regards

[chillerman2006]

Hi Buddy

not my area mate.... but would be presumptious in thinking it will be based on your heat load & then there will be a calculation as to the air volume you would need to move, to reject the heat

I know quite a few of the designers use programmes for calcs, try this one it seems popular

http://www.et.web.mek.dtu.dk/coolpack/uk/download.html

R's chillerman

[buddy]

Hi Chillerman3006,

Thanks for your input and the link.

I know that it would be based on the heat load but what is the actual criteria as I mentioned on my OP?

Air Velocity?...Air changes per hour? etc etc etc?

There must be a minimum ventilation requirement...other wise all compressor rooms would not have ventilation fans fitted just to save on cost.

best regards


best regards

[chillerman2006]

Hi Buddy

was just thinking out loud mate....not my area so sorry can not give a good answer for you

there are a number on here that would know how to do this..... a few off the top my head

Peter_1, Magoo, Mad Fridgie, DesA, Tesla,

If you dont get a response, you could drop them a pm

am sure they would be happy to help

Peter & DesA are about in the evening & the others after 21:00 normaly

R's chillerman

[Brian_UK]

Not certain of these things but with Gas regulations there are minimum ventilation requirements based on boiler sizes (kW).

Also the maximum temperature allowed in the UK for boilers houses is 30°C to protect electrical services which should not be above that temperature.

Different equipment maybe but the electrics are the same.

[edit]
Came across this document, albeit American, that details the different calculations required depending on what sort of ventilation you are aiming for. Obviously Imperial units used, sory.

http://www.reta.com/convention/2008/...tech-paper.pdf

[buddy]

Hi Brian_UK,

Yes picked that up myself from the internet, however RETA is an Ammonia organisation so I would think the ventilation requirements are completely different than what is required for a 100 HP compressor rack operating on R22 refrigerant.

I,m thinking safety, fast evacuation etc

Thanks for searching though much appreciated.

[chillerman2006]

Hi Buddy

I have thought how to work this out... maybe its just magic

Regards Chillerman

[al]

Buddy

One way i would do it, and have done so for applications here, is data log the room for 7 days, place temperature monitors at high and low level and then "map" this, you now have a base line temperature load to go off.

So from there work out what temperature the room needs to be and the air changes needed, use this and go off transformer room which is probably the closest match.

http://www.alpinefan.com/alpineair_vent_calc.php

to be honest most are sized on the biggest extract that the room can take, hence the lack of calculations!!

al

[chillerman2006]

Nice one Al

everyone has missed these posts and buddy & I was wondering if anyone will actually reply

Regards Chillerman

[install monkey]

its best to cover ur arse, get a rep fr venilation wholesaler,explan the fact that the compressors dont run 24 7 let him size the fans and ductwork, that way your covered when a comp fails and the customer tells u that u designed the ventilation,obviously it was undersized!!.
Its all a blame game,so if u can deflect the blame u still smell of roses,also were fridgies not duct/ventilation gimps!!!!

[buddy]

Buddy

One way i would do it, and have done so for applications here, is data log the room for 7 days, place temperature monitors at high and low level and then "map" this, you now have a base line temperature load to go off.

So from there work out what temperature the room needs to be and the air changes needed, use this and go off transformer room which is probably the closest match.

http://www.alpinefan.com/alpineair_vent_calc.php

to be honest most are sized on the biggest extract that the room can take, hence the lack of calculations!!

al

Hi Al,

Thanks for your input,

Good idea about the temp measurements etc, however how would I know what air changes are needed, 5, 10 30??..where would I get this information from for a 100 HP compressor rack?

And what about the ventilation calcs for a new compressor room?

Thanks for the link as well.

best regards

,

[buddy]

Buddy

One way i would do it, and have done so for applications here, is data log the room for 7 days, place temperature monitors at high and low level and then "map" this, you now have a base line temperature load to go off.

So from there work out what temperature the room needs to be and the air changes needed, use this and go off transformer room which is probably the closest match.

http://www.alpinefan.com/alpineair_vent_calc.php

to be honest most are sized on the biggest extract that the room can take, hence the lack of calculations!!

al

Hi Al,

Thanks for your input,

Good idea about the temp measurements etc, however how would I know what air changes are needed, 5, 10 30??..where would I get this information from for a 100 HP compressor rack?

And what about the ventilation calcs for a new compressor room?

Thanks for the link as well.

best regards

,

[buddy]

Just for your information I emailed a mate of mine who works for Hill-Phoenix in the States and he came back with a figure of 100 CFM per 1 Compressor Horsepower.

I did ask him where this figure came from and he says he "thinks" its from Copeland, not sure.

So 10,000 CFM for a 100 HP Compressor rack, but not confirmed?

I shall contact Copeland/Emerson in the US and see if I can get a straight answer from them and I,ll post the answer on this thread.

In the mean time anybody else got any ideas/information?...I didnt think it would be so hard to find the information?

Hey Chllerman2006...Thanks for your support.

best regards

[buddy]

Hi Install Monkey,

Good idea always to cover your arse, but where I am working there aint no reps from ventilation wholesalers...and if there was I would not trust them.

I'm basing that on past experience.

Thanks for your input.

best regards

[al]

Buddy

The site i attached has an air change recommendation for an internally positioned transformer, these are normally sited outdoors so i think this would well cover you and you can give the customer this info and get them to sign off on it, ultimately it is the customers instruction that you will be acting on!(that's what i do)

Al

[mad fridgie]

You have 2 issues to look at
First the compressors are they suction cooled or air cooled, "does the compressor need air flowing over them to keep them cool" This is specific to the compressor make and model. ( not the same as your ventilation) are tech detail will be available. ( Purpose built fans to do the job)

Depending upon the application ( HT or LT) and operating conditions you can get up to 30% of the electrical input to the compressors reject directly from the compressor so 100Kw rack, say COP of 2, electrical input of 50kw, so compressor heat lost 15Kw, then you consider high losses (oil sep and discharge pipes) very specific, lets 5Kw. are then any other gains, electrical switch boards, VSDs, solar gains, hot water tanks. (assume some) another 5Kw. So total 25Kw.
Outside air temp 25 C leaving 30C load 25kw, air flow = 4200l/s (will kill it)

[D.D.KORANNE]

A book on ventilation for mechanical equipment rooms suggests the following :

8 CFM/BHP combustion air
2 CFM/ BHP ventilation

[buddy]

Hi D.D,

Apologies I don't really understand your post?

Do you mean 2 CFM per Compressor horsepower for ventilation requirements?

[buddy]

Hi mad fridgie,

The Compressors are 25 Horsepower Copeland compressors with suction gas cooled motors.

Copeland Model 6SLW 2500 AW/MD-OOO Compressors both application HT and LT operating on R22 Refrigerant. plus +45 degrees condensing.

Ambient average +32 degrees Centigrade.

[chillerman2006]

A book on ventilation for mechanical equipment rooms suggests the following :

8 CFM/BHP combustion air
2 CFM/ BHP ventilation

it dont also say you get 100% more use when loss a sqirt of juice does it

[Grizzly]

Hi Buddy.
To get back to your original question.
Plant room or "specialized Machinery space" layouts and ventilation Requirements are given in EN378.
I believe the 2008 version gives a lot more detail, as historically certain companies went around installing
nothing more than corrugated steel bike sheds or lean To's with 4 walls.
I would not be surprised if this is not what you are referring too?
It is quite detailed and even refrigerant specific!

Any respectable company should be able to advise.
From memory there minimum louvered grill sizes, door details and sizes. Even down to refrigerant alarm and ventilation requirements.
Another consideration is if the refrigerant leaked out and went "Bang". Would the fabric of the building the plant is in.
Provide a safe controlled blast area or would you have sheet steel flying around. Possibly in a public car park.
Obviously the main consideration is the safety of individuals but if applied properly the plant ability to "Breath" is enhanced also!

You have raised a good point with your customer, where if remedied everyone wins.
By the way EN378 is Law!

Grizzly

[buddy]

Just for your information I emailed a mate of mine who works for Hill-Phoenix in the States and he came back with a figure of 100 CFM per 1 Compressor Horsepower.

I did ask him where this figure came from and he says he "thinks" its from Copeland, not sure.

So 10,000 CFM for a 100 HP Compressor rack, but not confirmed?

I shall contact Copeland/Emerson in the US and see if I can get a straight answer from them and I,ll post the answer on this thread.

In the mean time anybody else got any ideas/information?...I didnt think it would be so hard to find the information?

Hey Chllerman2006...Thanks for your support.

best regards

This is copied and pasted from Emerson (Copeland) reply to my enquiry. -

"Two-stage compressors are equipped with a desuperheating expansion valve for interstage cooling, and no auxiliary cooling is required.
If compressors or condensing units are located in a machine room, adequate ventilation air must be provided to avoid an excessive temperature rise in the room. To allow for peak summer temperatures a 10°F. temperature rise is recommended, although a 15°F. rise in cooler ambients might be acceptable.

The most accurate calculation is to determine the total heat to be rejected by adding the compressor refrigerating
capacity at the design operating condition to the heat equivalent of the motor input. The CFM can then
be calculated by the formula…
BTU/HR
CMF = ºTD
For example, determine the machine room ventilation for an air cooled condensing unit operating at -25°F.
evaporator, 120°F. condensing with a net refrigeration capacity of 23,000 BTU/HR, 6,400 watts input to the
compressor motor, and a 1 H.P. condenser fan motor.

Compressor capacity 23,000 BTU/HR
Heat equivalent 6400 watts x 3.413 21,843 BTU/HR
Heat equivalent 1 H.P. fan motor 3,700 BTU/HR
Total Heat to be Rejected 48,543 BTU/HR
48,543 BTU/HR
CMF = 10º TD = 4.854 CFM
With remote condensers, approximately 10% of the heat rejected is given off by the compressor casting and the
discharge tubing, and the ventilation can be calculated accordingly.
For convenience, table 20A gives a quick estimate of
the ventilation air requirement if only the compressor
capacity is known.

COMPRESSOR LUBRICATION
An adequate supply of oil must be maintained in the crankcase at all times to insure continuous lubrication.
The normal oil level should be maintained at or slightly above the center of the sight glass while operating.
An excessive amount of oil must not be allowed in the system as it may result in slugging and possible damage
to the compressor valves.

Compressors leaving the factory are charged with naphthenic refrigerant oils. A complete list of acceptable
refrigerants and lubricants are listed on form #93-11.
The use of any other oil must be specifically cleared with the Emerson Climate Technologies, Inc. Application
Engineering Department. The naphthenic base oil has definite advantages over paraffinic base oils because
separation of refrigerant from paraffinic oils occurs at substantially higher temperatures with the same oilrefrigerant
concentration.
When this separation or two phase condition exists the oil floats on top of the refrigerant and the oil pump inlet at the bottom of the sump is fed almost pure refrigerant at start up. The resulting improper lubrication can result in bearing failure. Because
of the lower separating temperature of naphthenic oil, the possibility of two-phasing is greatly reduced.
Copelametic® compressors are shipped with a generous supply of oil in the crankcase.

However the system may require more or less oil depending on the refrigerant charge and the system design.
On field installed systems, after the system stabilizes at its normal operating conditions, it may be necessary to add or remove oil to maintain the desired level.
OIL PRESSURE SAFETY CONTROL
A major percentage of all compressor failures are caused by lack of proper lubrication. Improper lubrication or the
loss of lubrication can be due to a shortage of oil in the system, logging of oil in the evaporator or suction line due
to insufficient refrigerant velocities, shortage of refrigerant, refrigerant migration or floodback to the compressor
crankcase, failure of the oil pump, or improper operation of the refrigerant control devices.
Regardless of the initial source of the difficulty, the great majority of compressor failures due to loss of lubrication
could have been prevented. Although proper system design, good preventive maintenance, and operation
within the system’s design limitations are the only cure for most of these problems, actual compressor damage
usually can be averted by the use of an oil pressure safety control.
An oil pressure safety control with a time delay of 120 seconds is a mandatory requirement of the Emerson
Climate Technologies, Inc. warranty on all Copelametic® compressors having an oil pump. "

[buddy]

Just for your information I emailed a mate of mine who works for Hill-Phoenix in the States and he came back with a figure of 100 CFM per 1 Compressor Horsepower.

I did ask him where this figure came from and he says he "thinks" its from Copeland, not sure.

So 10,000 CFM for a 100 HP Compressor rack, but not confirmed?

I shall contact Copeland/Emerson in the US and see if I can get a straight answer from them and I,ll post the answer on this thread.

In the mean time anybody else got any ideas/information?...I didnt think it would be so hard to find the information?

Hey Chllerman2006...Thanks for your support.

best regards

This is copied and pasted from Emerson (Copeland) reply to my enquiry. -

"Two-stage compressors are equipped with a desuperheating expansion valve for interstage cooling, and no auxiliary cooling is required.
If compressors or condensing units are located in a machine room, adequate ventilation air must be provided to avoid an excessive temperature rise in the room. To allow for peak summer temperatures a 10°F. temperature rise is recommended, although a 15°F. rise in cooler ambients might be acceptable.

The most accurate calculation is to determine the total heat to be rejected by adding the compressor refrigerating
capacity at the design operating condition to the heat equivalent of the motor input. The CFM can then
be calculated by the formula…
BTU/HR
CMF = ºTD
For example, determine the machine room ventilation for an air cooled condensing unit operating at -25°F.
evaporator, 120°F. condensing with a net refrigeration capacity of 23,000 BTU/HR, 6,400 watts input to the
compressor motor, and a 1 H.P. condenser fan motor.

Compressor capacity 23,000 BTU/HR
Heat equivalent 6400 watts x 3.413 21,843 BTU/HR
Heat equivalent 1 H.P. fan motor 3,700 BTU/HR
Total Heat to be Rejected 48,543 BTU/HR
48,543 BTU/HR
CMF = 10º TD = 4.854 CFM
With remote condensers, approximately 10% of the heat rejected is given off by the compressor casting and the
discharge tubing, and the ventilation can be calculated accordingly.
For convenience, table 20A gives a quick estimate of
the ventilation air requirement if only the compressor
capacity is known.

COMPRESSOR LUBRICATION
An adequate supply of oil must be maintained in the crankcase at all times to insure continuous lubrication.
The normal oil level should be maintained at or slightly above the center of the sight glass while operating.
An excessive amount of oil must not be allowed in the system as it may result in slugging and possible damage
to the compressor valves.

Compressors leaving the factory are charged with naphthenic refrigerant oils. A complete list of acceptable
refrigerants and lubricants are listed on form #93-11.
The use of any other oil must be specifically cleared with the Emerson Climate Technologies, Inc. Application
Engineering Department. The naphthenic base oil has definite advantages over paraffinic base oils because
separation of refrigerant from paraffinic oils occurs at substantially higher temperatures with the same oilrefrigerant
concentration.
When this separation or two phase condition exists the oil floats on top of the refrigerant and the oil pump inlet at the bottom of the sump is fed almost pure refrigerant at start up. The resulting improper lubrication can result in bearing failure. Because
of the lower separating temperature of naphthenic oil, the possibility of two-phasing is greatly reduced.
Copelametic® compressors are shipped with a generous supply of oil in the crankcase.

However the system may require more or less oil depending on the refrigerant charge and the system design.
On field installed systems, after the system stabilizes at its normal operating conditions, it may be necessary to add or remove oil to maintain the desired level.
OIL PRESSURE SAFETY CONTROL
A major percentage of all compressor failures are caused by lack of proper lubrication. Improper lubrication or the
loss of lubrication can be due to a shortage of oil in the system, logging of oil in the evaporator or suction line due
to insufficient refrigerant velocities, shortage of refrigerant, refrigerant migration or floodback to the compressor
crankcase, failure of the oil pump, or improper operation of the refrigerant control devices.
Regardless of the initial source of the difficulty, the great majority of compressor failures due to loss of lubrication
could have been prevented. Although proper system design, good preventive maintenance, and operation
within the system’s design limitations are the only cure for most of these problems, actual compressor damage
usually can be averted by the use of an oil pressure safety control.
An oil pressure safety control with a time delay of 120 seconds is a mandatory requirement of the Emerson Climate Technologies, Inc. warranty on all Copelametic® compressors having an oil pump. "

There you go..

[buddy]

I am still none the wiser.

Can anybody help in providing a STANDARD calculation for ventilation of Plant rooms with compressor Packs/Racks installed?

best regards

[fixit]

Buddy hello
what size is the compressor room?,
Rule of thumb Machine room 20 - 30 Air changes per hour,
Some compressor rooms are small and would not put in a fan with duty of less than 3,000M3/Hr.
Run the fan of a thermostat.
You say cross flow ventilation, is that where you put a plate axial fan on one wall and a large grill on the opposite wall, what is the ducting for?

[Emmett]

http://www.taylor-engineering.com/do...,%20Taylor.pdf

Give this link a try

[buddy]

Buddy hello
what size is the compressor room?,
Rule of thumb Machine room 20 - 30 Air changes per hour,
Some compressor rooms are small and would not put in a fan with duty of less than 3,000M3/Hr.
Run the fan of a thermostat.
You say cross flow ventilation, is that where you put a plate axial fan on one wall and a large grill on the opposite wall, what is the ducting for?

Hi Fixit,

Thank you for your reply.

The reason why I posted on RE was to hopefully get a straight answer or a calculation formula that may be considered standard vent requirements for compressor packs/racks, but it doesnt look as though it is that simple.

Where did you get the rule of thumb measurement of 20 - 30 air changes per hour from...what is the source?

Yes you are correct, cross flow from one end of the plant room to the other on opposite sides.

Surely the supermarket refrigeration company,s must do this calculation nearly every day, theremust be some communication between the ventilation company, the builder/project manager and the refrigeration compressor pack installer to get the right ventilation installed on a new store?

[buddy]

http://www.taylor-engineering.com/do...,%20Taylor.pdf

Give this link a try

Hi Emmett,

Thanks for the link.

I am aware of Ashrae standard 15 and also EN378 ventilation requirements for compressor rooms.
However those ventilation standards are "safety" standards in case of refrigerant leaks and also exposure to hazardous refrigerants, Ammonia, Hydrocarbons etc etc.

As what I am looking for is standard ventilation requirements for the compressor pack/rack say installed with 4 Bitzer or Copeland 25 Horsepower compressors in Supermarket application?

Anybody?

[Emmett]

Hi Emmett,

Thanks for the link.

I am aware of Ashrae standard 15 and also EN378 ventilation requirements for compressor rooms.
However those ventilation standards are "safety" standards in case of refrigerant leaks and also exposure to hazardous refrigerants, Ammonia, Hydrocarbons etc etc.

As what I am looking for is standard ventilation requirements for the compressor pack/rack say installed with 4 Bitzer or Copeland 25 Horsepower compressors in Supermarket application?

Anybody?

Sorry,
Thought that is what you were seeking. I have not got a clue what a rule of thumb would be but here is another link you may find helpfull.
http://www.suncam.com/authors/111Bal...achineRoom.pdf

[buddy]

Sorry,
Thought that is what you were seeking. I have not got a clue what a rule of thumb would be but here is another link you may find helpfull.
http://www.suncam.com/authors/111Bal...achineRoom.pdf

Hi Emmett,

Thanks again for the link.

On the document it says "2009 International code"

What code does this refer to, do you know?

[Emmett]

It is a code which has been adopted in nearly all of the United States.
http://en.wikipedia.org/wiki/Interna..._Building_Code

[mad fridgie]

I have given you the method of calculation, I do mind checking your results, but giving you the answer does not help you learn.
Break down each section showing your calculation method.

[buddy]

I have given you the method of calculation, I do mind checking your results, but giving you the answer does not help you learn.
Break down each section showing your calculation method.

Dear mad fridgie,

You are right of coarse so apologies for ignoring your previous post but it is so confusing with which method/formula do you calculate with as there seems to be so many out there and no set standard?

For my knowledge I shall try to work out the calculation on a separate post and kindly request your assistance as this will be my first attempt at this type of calculation.

This is exactly why I love RE, its such a great source of knowledge.

best regards

[buddy]

It is a code which has been adopted in nearly all of the United States.
http://en.wikipedia.org/wiki/Interna..._Building_Code

Hi Emmett,

Thank you for the information on the International building Code.

One question?

Where did you get the form from that you posted?

best regards

[buddy]

You have 2 issues to look at
First the compressors are they suction cooled or air cooled, "does the compressor need air flowing over them to keep them cool" This is specific to the compressor make and model. ( not the same as your ventilation) are tech detail will be available. ( Purpose built fans to do the job)

Depending upon the application ( HT or LT) and operating conditions you can get up to 30% of the electrical input to the compressors reject directly from the compressor so 100Kw rack, say COP of 2, electrical input of 50kw, so compressor heat lost 15Kw, then you consider high losses (oil sep and discharge pipes) very specific, lets 5Kw. are then any other gains, electrical switch boards, VSDs, solar gains, hot water tanks. (assume some) another 5Kw. So total 25Kw.
Outside air temp 25 C leaving 30C load 25kw, air flow = 4200l/s (will kill it)

Dear mad fridgie,

I have more information that may help me understand the calculation method (in blue font below).


Previous post –

You have 2 issues to look at
1) First the compressors are they suction cooled or air cooled = Suction gas cooled operating on R22 refrigerant.
2) "does the compressor need air flowing over them to keep them cool" = Yes (have posted Bitzer and Copeland calculation method).

This is specific to the compressor make and model. ( not the same as your ventilation) are tech detail will be available. ( Purpose built fans to do the job)

3) Depending upon the application ( HT or LT) = Have 2 compressor racks, 1 x LT and 1 x MT.
LT evaporating temp -35 Centigrade, MT evaporating at -15 Centigrade, Condensing both at +45 Centigrade

This where you lose me -
“ and operating conditions you can get up to 30% of the electrical input to the compressors reject directly from the compressor
For my knowledge where is this information from?

so 100Kw rack, say COP of 2, electrical input of 50kw, so compressor heat lost 15Kw, then you consider high losses (oil sep and discharge pipes) very specific, lets 5Kw.

For my knowledge where is this information from?

are then any other gains, electrical switch boards, VSDs, solar gains, hot water tanks. (assume some, no hot water tanks) another 5Kw. So total 25Kw.
Outside air temp 25 C leaving 30C

Outside air temp based on 40 C leaving 45 C

load 25kw, air flow = 4200l/s (will kill it)

For my knowledge how do you come to this result?

Best regards

[buddy]

Sorry Chaps,

I noticed I hadnt posted the Bitzer vent calculation....please see note below -

"If 4 x compressors, then if it is MT, you use 10% of condensing capacity
( this you need to calculate from our software),

Can you at least tell this is 4 cylinders or 6 cylinders compressors?

If it is 4 cylinder, 4H-25.2, estimate heat is 16.2kW, base on 10% of condensing capacity
(40.5kw x 4 = 162kW)"

best regards

[tl1972]

buddy,
Search for "Tyler System Installation Manual", it shows Machine Room Ventilation Requirements of 100 CFM / HP
for compressor rack system with remote air-cooled condenser (page 1-1).

Search for "Kysor Warren - Installation & Operation Manual", it shows "40 to 100 CFM per compressor horsepower depending on the ambient temperature" (page 29).

Search for 6.2.5.5.2 Minimum Ventilation in Canada B52, it shows "Whenever the refrigeration system is operating or whenever the room is occupied, a sufficient part of the
mechanical ventilation shall be operated to provide normal volumes equal to the greater of the following:
(a) 2.54 L/s/m2 (0.5 cfm/ft2) of machinery room area; or
(b) the volume required to prevent a maximum temperature rise above ambient greater than 10 ºC
(18ºF), based on all of the heat-producing machinery in the room".

For a rule of thumb, i would use 60 - 80 CFM / compressor HP.

[buddy]

buddy,
Search for "Tyler System Installation Manual", it shows Machine Room Ventilation Requirements of 100 CFM / HP
for compressor rack system with remote air-cooled condenser (page 1-1).

Search for "Kysor Warren - Installation & Operation Manual", it shows "40 to 100 CFM per compressor horsepower depending on the ambient temperature" (page 29).

Search for 6.2.5.5.2 Minimum Ventilation in Canada B52, it shows "Whenever the refrigeration system is operating or whenever the room is occupied, a sufficient part of the
mechanical ventilation shall be operated to provide normal volumes equal to the greater of the following:
(a) 2.54 L/s/m2 (0.5 cfm/ft2) of machinery room area; or
(b) the volume required to prevent a maximum temperature rise above ambient greater than 10 ºC
(18ºF), based on all of the heat-producing machinery in the room".

For a rule of thumb, i would use 60 - 80 CFM / compressor HP.

Hi tl1972,

Lots of information there.

Thank you very much.

best regards