Finally a Proper Solution to Create a 100% Reliable
17 September 2002
The electrical feedback signal received in the control room is for the plant control room engineers very valuable. False information could lead to unnecessary alarms or even worse a plant shutdown.
The unreliable signal is in practise created by the weak brackets used to mount the switches too. Since the only way to measure the position of a gate valve is to check the spindle position, we have to make a framework around the hand wheel. This type of support creates open and unprotected switches with loose hinging wiring. It is easy to understand that this doesn't function to anyone's satisfaction, moreover it is a nightmare for the maintenance engineer.
After several discussions with end users, who did have these problems, Netherlocks designed their VPI-M, which stands for Valve Position Indicator-Multi turn.
In contrary to the existing method the VPI-M is an integrated system. The whole unit is mounted under the hand wheel, doesn't have loose wiring and the switches are protected. Above this the VPI-M can be mounted without valve modification and even while the plant is in process. The adjustment point for the open and/or close signal is very simple adjustable by tightening just one screw. The switch that suits the client most can be installed always.
The VPI-M doesn't need, like an actuator, high power signals (380V), but only a control signals, which does reduce cost dramatically. The system is used worldwide, tested a proven by SHELL.
Therefore, in case actuators are too expensive and not really necessary the VPI-M is your reliable partner.
