Sterlco SPV Remote Proportioning Devices - Manual (Page 18)

Remote Proportioning Valve Chapter 4: Operation 18 of 28
Chapter 4: Operation
The SPV can be controlled by one of three different controls. See Chapter 3: Installation for
installation instructions.
• Knob box — Used with Autoloader hopper loaders. This control is supplied with
Model SPV-A.
• Stand-Alone control — Used with central vacuum system vacuum hoppers. This
control is supplied with models SPV-B and SPV-D.
• Hopper loader control — Used with 9953 and 9963 hopper loaders. The existing
control box for these models has the circuitry to control model SPV-C Remote
Proportioning Valves already installed.
4-1 Knob Box Operation
Knob box controls are used with Autoload Hopper Loaders and are supplied with the SPV-A.
The Knob Box has two knobs, a power switch, and a power indicator light. Install the knob
box as described in Section 3-2 on page 13.
Ratio Knob
The knob labeled RATIO controls the relative delivery proportion of Material A to Material
B, typically virgin and regrind. This knob may be adjusted in a range from all Material A and
no Material B to no Material A and all Material B.
These ratios are approximate. For a known proportion, use the weight test procedure in
Section 4-4 on page 21.
Cycle Seconds Knob
The knob labeled CYCLE SECONDS controls the total length of each proportioning cycle.
This knob may be adjusted from zero (0) to twenty (20) seconds to fine-tune the
proportioning operation to the convey time of the vacuum receiver being loaded.
For example, if the cycle time is 20 seconds and the Ratio knob is at 50/50, Material A will
convey for 10 seconds and Material B will convey for 10 seconds. The cycle repeats
automatically.
Power Switch and Indicator
The power toggle switch can be used to turn the Autoload Hopper Loader On and Off if the
power switch on the Autoloader is ON. The POWER ON light is illuminated when power is
applied. The knob box is supplied with twelve (12) feet of cable and can serve as a remote
On/Off switch.
Note: The knob box and Autoloader hopper loader power switches must both be ON
for the loader to operate.