Norgren Collateral

Solutions Q&A 13 3.5 Performance ? 3.5.1 Flow quoted? Flow characteristic is the measurement of the flow through the unit for a given deviation from the set outlet pressure. For example, take a regulator and set the pressure at 90 psig under no flow conditions. As the flow through the unit is increased then the actual outlet pressure falls away from the set pressure. This is called droop (from set). Normally IMI Norgren quotes regulator flow measured under the following conditions: Inlet pressure = 150 psig, set pressure = 90 psig and a 15 psig droop from set. See note on competition performance in 2.6.1. ? 3.5.2 What are regulation characteristics? Regulation characteristics show how the outlet pressure from the regulator varies when the inlet pressure varies (under constant or no flow conditions). For example, take a regulator set at 60 psig outlet pressure, with 150 psig at the inlet. If the inlet pressure reduces, ideally the outlet pressure would remain the same. However, in regulators with an unbalanced valve (eg R07) the outlet pressure actually increases slightly as the inlet pressure decreases. In regulators with balanced valves this variation is reduced. Standard regulators have an acceptable deviation for most pneumatic application and customers tend to be interested in regulation characteristics in critical applications only. Where this is so, consider using a precision regulator, or consult Application Engineering about ways to improve the performance of standard regulators. ? 3.5.3 What is the repeatability of a regulator? Repeatability can be defined in terms of changes in flow, inlet pressure or time. It is important to understand which the customer requires. a. Repeatability with respect to changes in flow: ie the ability of a regulator to hold a set pressure with increasing or decreasing flow. b. Repeatability with respect to time changes: ie the ability of a regulator to hold a set pressure over a time period. c. Repeatability with respect to inlet pressure changes: ie the ability of a regulator to hold a set pressure with changes in supply pressure. For more information refer to catalog graphs, or consult Application Engineering. 3.6 Simple regulator troubleshooting Malfunction Possible cause Remedy Regulator creep (increase in secondary pressure due to leak from primary). Dirty or cut valve elastomers. Nick in valve seat. Replace or clean valve. If body or valve seat is damaged it can be replaced on some models. On others replacement of complete regulator is required. Won't relieve sec- ondary pressure. Non-relieving diaphragm assembly. If this feature is required, replace with relieving type diaphragm assembly. Won't reach desired pressure. Regulating spring with low spring rate. Use regulating spring with spring rate designed to cover desired range. Excessive leak from relief hole. Damaged relief seat. Ruptured diaphragm. Leakage past valve causing secondary to increase somewhat and open relief seat. Replace diaphragm assembly. Replace or clean valve. Regulator chatter. A resonant condition is generally only encountered under a certain set of conditions of flow and pressure and then only in some applications in which regulator couples with other system components. Replace spring with a higher pressure range spring. Replace with a piston type regulator since they have less tendency to chatter. Regulator difficult to adjust. Adjusting screw or knob locking device in locked position. Contaminants in adjusting screw threads. Pull to unlock knob and adjust; push knob to lock. Threaded adjusting screws: loosen lock nut, remove adjusting screw, clean thread and lubricate. Place some lubricant on tip of screw.

• Cover