Oscillation, if it occurs, may be in the form of a sputter, “motor boat”, pop, click, or hiss as the interface is modulating pressure up or down to achieve set point. Some reasons are as follows:
1. CAPACITY
Not enough branch line capacity. The minimum requirement for the pneumatic interface is two cubic inches of branch line volume. Without the required capacity the pressure can change faster than the valve(s) can respond.
2. LEAKS
Excessive branch line leaks can be caused by:
- a. Gauge port leak.
- b. Controlled device bleeds too much (i.e. Receiver Controller).
- c. Branch line connections leak.
- d. Debris, oil or water contamination in interface valve.
- e. Leak around orifice.
- f. Leak in interface valve.
- g. Leak in manifold.
- h. Transducer gasket missing or misaligned.
3. INPUT SIGNAL
AC line noise induced onto input signal.
4. POWER
Power supply voltage too low or fluctuates too low.
5. PRODUCT DEFECTS
- a. Defective valve.
- b. Defective manifold.
- c. Incorrect calibration (someone has tampered with trim pots).
- d. Defective circuit.
6. MAIN AIR PRESSURE
Main pressure is too high or erratic
7. ENVIRONMENT
- a. Excessive vibration.
- b. Water or condensation in air supply.
