VMAC – Vehicle Mounted Air Compressors
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10
These are nominal values only. Tests should be performed to
confirm that the desired CFM has been achieved due to variations in
hydraulic system efficiency, load and flow.
If the compressor is being installed on a truck that already has a
functioning hydraulic system, check the specifications for that system
to ensure that it meets minimum requirements.
The information in this manual is based on a fixed displacement
pump. Special considerations may be required for a variable
displacement pump.
2.4 Electrical Requirements
The PREDATAIR requires a steady 17 Amps @ 12 VDC to operate.
A 30 Amp fuse or circuit breaker is recommended.
To assure an un-interrupted supply of power, the ground wire should
be routed either to the negative terminal of the battery or to a
substantial, fully grounded point on the vehicle chassis, located in an
area which will provide a good ground at all times.
Power should be ignition switched through a relay to reduce the risk
of battery drain when the engine is off. Main power should be tapped
directly from the positive terminal of the battery through a relay with a
contact rating of at least 20 Amps. Using a relay allows the heavy
gauge power wire to be routed directly and permits the use of a light
(18 AWG) wire between the relay and the control switch (Figure 7).
2.4.1 Wire Size Selection
Selecting the correct wire size is vital for proper operation. If the wire
size is too small, voltage drop will be excessive and the compressor
will operate erratically. Measure the length required for both the
power wire and the ground wire, add them together and select the
correct wire size from Table 1.
Total length of Power wire PLUS Ground wire
Recommended Wire Gauge
Less than 5 ft.
12AWG
5 ft. to 8 ft.
10AWG
More than 8 ft.
8AWG
Table 1 – Wire gauge size
