Pneumatic PV Sensor (PPVS)

A closed mould held together with vacuum is basically held with atmospheric pressure so any injected resin exceeding this pressure will distort the mould open. To avoid this, the mould designer has two options, either build the mould much stronger or simply provide the machine with a control system so that the internal mould pressure never exceeds
atmospheric pressure.

Some suppliers attempt to do this at the machine nozzle but as many have come to realise this is not accurate enough and a pressure sensing INSIDE the mould cavity, providing the machine with a signal to reduce speed as the pressure builds, is the only accurate way to guard against over pressure inside the mould.

For several years MVP address this requirement with the well known PVSensor , a small, inexpensive electronic sensor linked to the machine flow control circuit. However even though the PVSensor system operates the pneumatic machine control at low 12VDC supply the ideal answer is to avoid any electrical power and maintain pure pneumatics on the whole system.

To address this, the MVP Advanced Design Group was challenged especiallay in view that a pressure change of only 30-40 mb (0.75 psi) has to be sensed for this application.

The new ALL pneumatic PVSensor, now being introduced, is a realisation of this ideal. Embodied in a neat PTFE sensor housing of remarkable sensitivity for a pneumatic device and designed to fit the MVP Universal mould insert system, it gives exactly the same precision control of the machine flow and pressure that the earlier electronic version does. An added advantage is that it is marketed at half the price of the earlier electronic version and being pneumatic, it is considerably more robust for the workshop environment.

In operation the Pneumatic PVSensor system needs only one air supply which is conveniently available, when injection starts, from the Turbo Autosprue injection valve open signal, so no added lines are required to power up. The output is a single 4mm signal line which plugs into any of MVP's injection MPG fitted machines and that is it. Total machine pressure control from mould internal pressure is available from a safe, robust pure pneumatic system.

Sensitivity: Between 0.2 bar and 1.0 absolute
Hysteresis: Better than 40 mb
Repeatability:  +/- 1% of FSD.
Air switch:
  Operating pressure:  2-8 bar (30 -120 psi) filtered at 5 micron
  Flow at 6 bar:  <70 Nl/min ( 2.5 cfm)
  Mechanical life at 6 bar:  (90 psi) - 10 million connections barb style suitable for semi rigid
  tubing 2.7 ID 4 OD (0.106" x 5/32")
Main Body:
  In contact with Resin:  PTFE
  In contact with fumes:  PTFE, Silicone diaphragm and stainless steel
  Housing:  Machined aluminium
  Adjustment:  Allen wrench 2.0 AF (0.080")
  Dimensions:  overall 96mm x 51mm dia.(3.78 x 2.0")
  Weight:  262 gm (9.24oz)