# Thread: How to figure out Strength Test Criteria for R404a Refrigerant?

1. ## How to figure out Strength Test Criteria for R404a Refrigerant?

Hi, I'am new to Refrigeration. I'am doing course which will allow me to work in the field as a Refrigeration Engineer. Good that website like that one exists. So I can ask someone about things I don't know.

My question is like in title of this topic.

How to count the Strength Test Pressure for split unit (Air/Con)?

2. Hi, Rob

Welcome to our Forum

3. Hi, Rob

First of all. You need to know in which geographic zone you live.

4. What you mean by zone?

5. Hi Rob here is how you work it out for R-404a for an air cooled condenser.

Low side 32 degrees = 13.91bar High side 55 degrees = 24.54bar
13.91x1.1=15.3bar) 24.54x1.1=27bar
13.91x1.5=20.7bar) 24.54x1.5=36.8bar
Range is between 15.3-20.7bar Range is between 27-36.8bar

hope that helps

6. Originally Posted by Rob
What you mean by zone?
By zone I mean the standard ambient temperature. Generally in the world we can find two different climate zones. The places where ambient temperature is taken as 43 Celsius (Asia, Africa, Australia, and some parts of middle and south America). Everywhere else the ambient is equal to 32 degree of Celsius.

 32c Ambient 43c Ambient High pressure side Air cooled Condenser 55c 63c High pressure site Water Cooled Condenser 43c 43c Low pressure side 32c 43c

Now we need to find out the pressure of our refrigerant at 32C for low side pressure and 55C for high side pressure. To do that we need to use comparators.
Refrigerant R404a at 55 degree Celsius is under 24.54(Bar) of pressure and in low side is equal to 13.91(Bar).

We need to apply the formula to count a High side strength pressure.
The H.P Strength test = Ps(highside)x 1.1 and x 1.5
The H.P Strength test = 24.54 x 1.1 = 27 and 24.54 x 1.5 = 36.81
The H.P Strength test = 27(Bar)(minimum) and 36.81(Bar)(maximum)

Just before we apply the OFN in to the system for strength test we need to make sure that all devices on H.P side are able to take that high pressure. If one of the devices can't co-op with pressure of 36.81 (Bar) then we need to go for minimum Strength Test Criteria which in this scenario as we counted is equal to 27(Bar)

Formula to count Low Side Pressure, strength test.
The L.P. Strength test = Ps(Low side) x 1.1
The L.P. Strength test = 13.91 x 1.1
The L.P. Strength test = 15.3(Bar)

The Strength Test Criteria for low side is equal to 15.3(Bar)

*H.P.-High Pressure Side of refrigeration system.
*L.P.-Low Pressure Side of refrigeration system.

7. Thanks guys for all...

8. Thanks great topic

9. Ya nice topic cheers lads

10. Thanks great topic!

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