Enovation Controls Murphy DF Series, Installation And Operation Manual

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Section 15 00-02-0831
2013-03-21 - 6 -
Installation of a Volume Air Cell
This section provides installation and
operation information for using a DF755 level
switch with a
Murphy MAC1 Volume Air
Cell .
Overview
When attached to the DF755 level switch, the MAC1 Volume Air Cell can monitor water levels
on a sump, activate alarms, or start a pump directly. The
MAC1 Volume Air Cell
is non-
corrosive. Stainless steel ¼-20 mounting studs are provided with the unit.
The MACT1 Tubing Kit provides 4 ft (1.2 m) of flexible, non-corrosive ¼ in (6 mm) tubing (cut
to fit). The kit also includes fittings necessary to attach tubing
Volume Cell Operation
As liquid rises around the volume cell, it compresses the air inside the cell and forces it up in
the sensor line. As the water level continues to rise, the air pressure increases. In time
sufficient pressure is applied to activate the internal snap-switch, this starts the pump. As the
liquid level is pumped down, pressure decreases, the snap-switch reverses and the pump
stops. The pump is held in a standby condition. An air purge may be required in the sensor
line. For additional information, consult Enovation Controls.
Choosing a Volume Cell
The volume cell should be constructed of material which will be unaffected by the liquid being
measured. For proper pressure to level ratio, the minimum dimensions of the volume cell
should be 6 inches (152 mm) inside diameter and 3 inches (76 mm) inside depth. The sensor
line can be of any diameter or material either flexible or solid, as long as it is of sufficient length
to reach from the volume cell to the desired location for the DF755. All fittings and connections
should be airtight to avoid loss of charge. Tube lengths longer than 4 ft (1.2m) should have a
provision for intermittent air purging.
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