© NOVATEC, Inc. 2013 All Rights Reserved
VL-VLP IM 4-12-2013
10
Dump Time (B5 T)
, measured in seconds, is the setting for how long the loader will remain at rest
after loading, to allow material to evacuate the loader. This setting may be increased in case the
material is very slow moving and/or to provide an extended OFF period for the loader (IE: if the
loader is used to off-load a granulator).
Blowback Count (B11)
, is the number of blowback pulses that occur following loading for the
compressed air system to clean the filter(s). Compressed is blown down through the filters in the
opposite direction of the vacuum loading air, blasting collected fines and dust from the filter media
and into the loaded material. Typically, more blasts will clean the filters better and extend the
time between manual filter cleaning and provide more efficient loading. However, compressed air
is expensive and too many blasts waste this resource. Also, blasts that extend beyond the dump
sequence may actually be strong enough to create dusting issues around the loader.
Prop Valve A Time (B16 T) and Prop Valve B Time (B18 T)
, each measured in seconds, is the
amount of time dedicated to the loading of two materials with the use of an optional, external
Proportioning Valve. The Proportioning Valve is installed on the material inlet of the VL or VLP
loader (see separate instructions, accompanying the valve) and shuttles internal plungers
between allowing A (typically virgin) and B (typically regrind) materials to be loaded during the
course of the Motor-On time. Time setting A counts down during loading at which time the valve
switches to allow the B time setting to take over. A and B will repeat until the Motor-on time
expires.
Short A and B time set
tings will allow multiple ‘layers’ of virgin and regrind materials to be loaded
for rough ‘mixing’ of the two materials during loading. However, short cycles require each flow of
material to start, then stop, possibly resulting in very little material being conveyed to the loader.
Trial and error settings of Motor-on time and A and B times are suggested to optimize these
settings.
9- USE OF PROPORTIONING VALVES
Proportioning valves are a convenient method for introducing regrind into the process while
vacuum loading of virgin material. The proportioning valve is typically installed onto the material
inlet of the receiver and is connected to the central control system, or an accessory control
specifically designed for proportioning valve operation.
Note that a proportioning valve should never be relied upon for
accurate
mixing of two materials,
but are only a process convenience for loading a second material (typically regrind). An ideal use
of a proportioning valve is emptying a granulator of reground material, in quantities known to not
exceed the limitations or specifications of the process.
If requirements for the proportioning
require more accuracy, consult with
your supplier regarding the use of a
blender in lieu of a simple
proportioning valve.
Solenoid: Connection to control
and connection to compressed
air supply.
Material #1 inlet,
typically Virgin
Material #2 inlet,
typically Regrind
Material Outlet, connected
to receiver Inlet
External Proportioning Valve
