Example

Suction Line

Since one of the direction changes is a long sweeping turn, the equivalent length of one elbow will be considered. Since the Cal-coolator is designed for ARI Conditions of 40oF evaporator and 105oF condenser (4°C and 40°C), the cooling load must be adjusted for the higher condensing temperature of an air cooled unit (95°F ambient temperature+30°F=125°F). Using the equation

Load(tons) X (0.005 X Condensing Temp. °F + 0.45) = Adjusted Load (tons)

5 tons X (0.005 X 125 + .45) = 5.37 adjusted tons

With adjusted load = 5.37 tons

Suction line pressure drop = 3 psi

Equivalent lengths: 1elbow(estimated) = 5 ft., piping = 25 ft., total = 30 ft. (see Guidelines)

Match 3 psi pressure drop with 30 feet at the top window

At the suction line window (third from the top), note a pipe diameter of 7/8" will have a capacity of 5.6 ton refrigeration load, or enough to handle the 5.37 ton adjusted load.

From the chart in the guidelines, a 7/8" elbow has an equivalent length of 5.3 ft. So the suction line would have an equivalent length of (25+5.3) 30.3 feet. The final pressure drop is computed by matching 5.37 tons with a 7/8" suction line in the suction window. For a 30.3 feet equivalent length the pressure drop is 2.8psi. This is an acceptable suction pressure drop.

A check of refrigerant velocity is done to be certain of proper oil flow. With the bottom two windows of the chart. 5.37 tons is matched with a 7/8" line.

The "suction" pointer indicates a velocity of approximately 3200 ft/min. This is greater than the minimum velocity for horizontal or vertical lines and less than the maximum recommended velocity of 4000 ft/min.

Liquid Line

Since one of the direction changes is a long sweeping turn, the equivalent length of one elbow will be considered. Since the Cal-coolator is designed for ARI Conditions of 40°F evaporator and 105°F condenser (4°C and 40°C), the cooling load must be adjusted for the higher condensing temperature of an air cooled unit (95°F ambient temperature+30°F=125°F). Using the equation

Load(tons) X (0.005 X Condensing Temp. °F + 0.45) = Adjusted Load (tons)

5 tons X (0.005 X 125 + .45) = 5.37 adjusted tons

With adjusted load = 5.37 tons

Suction line pressure drop = 3 psi

Equivalent lengths: 1elbow(estimated) = 5 ft., piping = 25 ft., total = 30 ft. (see Guidelines)

Match 3 psi pressure drop with 30 feet at the top window

At the suction line window (third from the top), note a pipe diameter of 7/8" will have a capacity of 5.6 ton refrigeration load, or enough to handle the 5.37 ton adjusted load.

To keep pressure drop less than 6 psi a 1/2" liquid line is matched with 5.37 tons and a pressure drop of 1.45 psi is found in the top window.

In the lower two windows of the chart, match 1/2" liquid line with 5.37 tons . The liquid line "site glass" is white and therefore the liquid line velocity is less than 360 ft/min. (Move the slide to the left and see that a 1/2" line can be use for loads up to 8 tons load before the liquid "site glass" turns black)