Download
the Series 700 Detailed Datasheet in Acrobat Format
The
Delta Controls Model 718A uses the same mechanism
and body as the Model 717A. The difference is that it is equipped with an additional
displacer and switch station. A precise on/off action occurs in the appropriate
switch station when the liquid level surface passes the elevation of the related
displacer element. The Model 718A is commonly used to provide a "High" warning
alarm, a "High-High" shutdown action, a "Low" warning alarm, and a "Low-Low"
shutdown action. The type service is found in processes where a heater must
not be uncovered and the tank must not overflow. Another application is emptying
a sump using three pumps. Each of the three top displacers starts a pump, the
bottom displacer simultaneously stops all three pumps.
The
Delta Controls Model 718D utilizes a mechanism
and displacers similar to the Model 718a four-point alarm. The difference
is that an adjustable differential device has been added and only three switch
stations are utilized. The lower switch station activates when the liquid
level covers the "L2" displacer, and stays activated until the liquid level
drops below the "L1" displacer. The middle switch station activates when the
liquid level covers the "L3" displacer and stays activated until the liquid
level drops below the "L2" displacer. The upper switch station activates when
the liquid level covers the "L4" displacer and stays activated until the liquid
level drops below the "L3" displacer. This is very versatile unit and can
perform complex control functions. Common applications include: A. Control
3 pumps B. Control 2 pumps with a high or low alarm C. Control 1 pump with
a high and low alarm D. Provide staging for operation of 3 pumps on storm
water inflow conditions