5
MEASURE TEMPERATURE DIFFERENCE (Delta T) Continued
FIRST PRESS:
T1 – T2;
SECOND PRESS: T1 – T3;
THIRD PRESS: T2 – T3;
FOURTH PRESS: DELTA T DISPLAY OFF.
MEASURE PRESSURE
Connect a Cooper Pressure Transducer to either U1 or U2 (or both). The MFM300 will sense
the probe(s) and display the pressure measurement(s) with the appropriate U1 or U2 label.
Before connecting the transducer(s) to the cooling system, zero the pressure reading(s) (refer
to Setup section on zeroing the pressure probes and setting altitude).
NOTE: AT SEA LEVEL, THE PRESSURE READING SHOULD BE 0 PSI (0 KPA) WHEN NOT
CONNECTED TO A COOLING SYSTEM. AT ELEVATIONS ABOVE SEA LEVEL THE
DISPLAY WILL SHOW A NEGATIVE PRESSURE READING (-0.5 PSI / 1000
FEET ALTITUDE). CONNECT THE TRANSDUCER(S) TO THE COOLING SYSTEM ACCESS
PORTS, USING BEST INDUSTRY PRACTICES, TO BEGIN MEASURING SYSTEM
PRESSURE.
MEASURE SYSTEM SUPERHEAT / SUB-COOLING
Select the refrigerant: The selected refrigerant is displayed when in Superheat / Sub-cooling
Mode, or when viewing pressure / temperature charts. To change the refrigerant, press the REF
button. The “Up / Down Arrows” will appear beside the refrigerant name. Use the UP / DOWN
ARROW buttons to scroll to the desired refrigerant and then press the ENTER or REF button.
Press the CANCEL button to abandon changes.
Add and / or change refrigerants: The MFM300 stores P / T data from 15 popular refrigerants
that reside in permanent memory. There is room in the memory for up to five more
refrigerants. New refrigerant P / T data can be downloaded from the Cooper-Atkins website
(www.cooper-atkins.com/mfm.asp) using the MFM300 Toolbox and the optional computer
connection cable.
CALCULATE SUPERHEAT / SUB-COOLING
The MFM300 can be used as a Superheat / Sub-cooling calculator. Connect the temperature
probes to the system and press the SH button. Select the refrigerant and press the ENTER
button. Since there are no pressure transducers connected, system pressure will default to
25 PSI for superheat and 75 PSI for Sub-cooling. You may manually enter the actual pressure
value from the manifold gauge into the MFM300 using the UP / DOWN ARROW buttons. Once
the pressure is entered for Superheat, use the SHIFT button to move to Sub-cooling, where
pressure is manually entered the same way. Remember that the values shown in this mode are
not dynamic.
MEASURE DYNAMIC SYSTEM SUPERHEAT / SUB-COOLING
Measuring dynamic system Superheat or Sub-cooling requires both a temperature probe
and a pressure transducer. The refrigerant type selected on the display must match the
refrigerant type used in the system. Refer to the section Select the Refrigerant. For Superheat
measurement, connect the temperature probe to T1, and the pressure transducer to U1. For
Sub-cooling measurement, connect the temperature probe to T2 and the pressure transducer
to U2. To measure superheat, attach the temperature probe to the system suction line near the
compressor. Attach the pressure transducer to the low side access port. Press the SH button.
