Sterlco SPV Remote Proportioning Devices - Manual (Page 19)

Remote Proportioning Valve Chapter 4: Operation 19 of 28
4-2 Standalone Control Operation
The Stand-Alone Control is provided with SPV models B and D and is used with central
vacuum system operated vacuum hoppers. The Stand Alone control box has these features:
Power Switch
The power switch on the stand-alone box must be in the ON position during operation. If the
power switch is turned off during operation, the SPV will stop conveying and the central
vacuum system will sense a high vacuum condition and initiate a blowback cycle.
Fuse Holder
The 2-amp fuse for the Stand-Alone Box is conveniently located on the faceplate of the
enclosure and can be easily replaced. Keep a spare fuse on hand.
Conveying Time Range Selector Potentiometer
The conveying time range can be set in seconds, minutes, hours, or tens of hours by turning
the unit selector potentiometer (or pot) located in the lower right corner of the timer face.
Timer Dial Increment Selector Potentiometer
The timer dial increments may be set by turning the increment selector potentiometer (or pot)
located in the lower left corner of the timer face.
Material A Timer
The conveying time for Material A is controlled by dialing the orange or ON axial dial to the
desired time.
Material B Timer
The conveying time for Material B is controlled by dialing the yellow or OFF radial dial to
the desired time.
Note: Due to the variance of flow characteristics between different materials, the
ratio set by the two material dials will not necessarily provide the same ratio of
material. Some adjustment of convey times may be necessary to achieve the
desired mixture. See Section 4-4 on page 21 for an explanation and a method
of determining and tuning actual conveying rates.