Bulletin V-10 Operation, Installation & Maintenance Manual Series 38R Self-Operating Temperature Regulators Actuator Option 2 Shown Indicating and Non-indicating
Series 38R ••• Self-Operating Regulators Operation, Installation & Maintenance Manual Operation, Installation & Maintenance Manual TABLE OF CONTENTS Principles of Operation of the Regulator 3 Identifying Your Unit Pressure and Temperature Limits 4 Regulator – Installation 5 Sensing Bulb – Location & Installation 6 Placing Regulator into Operation & Setting Control Point 7 Routine Service 8 Stem Seal Packing 9 Checking the Regulator for Proper Action 10-11 Valve Body Assembly 12-13 Reve
Series 38R ••• Self-Acting Temperature Control Valves Operation, Installation & Maintenance Manual PRINCIPLES OF OPERATION OF THE REGULATOR The W.E. Anderson Model 38R Temperature Regulator operates on the vapor pressure principle. The thermally sensitive bulb of the instrument contains a fluid that creates a vapor which increases or decreases in pressure as the sensing bulb temperature increases or decreases.
Series 38R ••• Self-Acting Temperature Control Valves Operation, Installation & Maintenance Manual PRESSURE AND TEMPERATURE LIMITS Maximum Static Pressure Valve bodies in 1/2” through 2” sizes are rated for 250 PSIG (17.2 bar) max. Valve bodies in 21/2” through 6” sizes are rated for 125 PSIG (8.6 bar) max. Maximum Pressure Drop through the Valve The “Pressure Drop” is the change in pressure of the process fluid as it passes through the valve.
Operation, Installation & Maintenance Manual Series 38R ••• Self-Acting Temperature Control Valves INSTALLATION Deciding the LOCATION for the Regulator The regulator should be installed in an accessible location on horizontal piping. Possible damage from moving parts, splashing of corrosive liquids, vibration, heat, fluid pulsations, etc., should be considered in deciding the location. Similar consideration should also be given to the connecting tubing and bulb.
Series 38R ••• Self-Acting Temperature Control Valves Operation, Installation & Maintenance Manual SENSING BULB SENSING BULB LOCATION The location of the sensing bulb is important. Use of a thermowell is always recommended, especially in pressurized systems. The bulb or thermowell must be totally immersed in an average temperature location which is representative of the whole volume being controlled.
Series 38R ••• Self-Acting Temperature Control Valves Operation, Installation & Maintenance Manual PLACING THE REGULATOR INTO OPERATION AND SETTING THE CONTROL POINT Using the supplied 1/4” rod, turn the 13/4” adjusting screw to a position on the “0 to 8” reference scale to a position that approximately corresponds to the relative position of the desired control point within the adjustable range.
Series 38R ••• Self-Acting Temperature Control Valves Operation, Installation & Maintenance Manual ROUTINE SERVICE Since this instrument is self-contained and practically trouble free, very little maintenance is required. It is important to keep the stem clean and free of deposits where it passes through the stem seals at the bonnet. An occasional drop of oil on the stem will aid in eliminating mineral deposits and maintaining a free running stem for accurate regulation. See Figure.
Series 38R ••• Self-Acting Temperature Control Valves Operation, Installation & Maintenance Manual STEM SEAL PACKING The regulator uses PTFE “V” ring packing sets with stainless steel male and female adapters used as end rings, with a stainless steel compression spring. This spring loading of the packing maintains proper compression of the rings and also compensates for wear that occurs at the seals.
Series 38R ••• Self-Acting Temperature Control Valves Operation, Installation & Maintenance Manual CHECKING THE REGULATOR FOR PROPER ACTION The thermal actuator will become inoperative if any leak occurs in the thermal system, allowing the pressure to escape from the system. This will in turn cause the bellows to retract upward causing the regulator to control as if the measured process had turned very cold. i.e. A heating valve will fully open and a cooling valve will fully close.
Series 38R ••• Self-Acting Temperature Control Valves Operation, Installation & Maintenance Manual CHECKING THE REGULATOR FOR PROPER ACTION (continued) INSPECTING Valve Body Assembly 1. Remove the Valve Body Assembly from the actuator. (See section on “Removing Valve Body Assembly”) 2. By gloved hand, alternately push the valve stem down and pull up. There should be at least 1/4” of motion. 3. If no motion is seen, the valve is jammed. A.
Operation, Installation & Maintenance Manual Series 38R ••• Self-Acting Temperature Control Valves VALVE BODY ASSEMBLY REMOVING Valve Body Assembly 1. Allow the sensing bulb on the actuator to cool to the bottom of the nominal range. Artificially cool with ice if necessary. 2. Record the current actuator adjusting screw setting relative to the reference scale. 3. Turn the actuator adjusting screw in (up) to reference number 8. 4. Hold the hexagonal actuator stem with a 5/16” wrench.
Operation, Installation & Maintenance Manual Series 38R ••• Self-Acting Temperature Control Valves VALVE BODY ASSEMBLY (continued) REPLACING Valve Body Assembly 1. Unless already completed, install two locknuts onto valve stem. A) Thread locknuts loosely onto the valve stem. B) Push or pull the valve stem as appropriate to fully CLOSE a two way valve. For a three-way valve pull the stem full OUT. C) Set the topmost locknut to the dimension shown and tabulated in Figure 6.
Series 38R ••• Self-Acting Temperature Control Valves Operation, Installation & Maintenance Manual REVERSING THE VALVE ACTION 1/2” – 2” Valve Sizes Only Direct-Acting valves close with temperature increase and inward stem motion. On a regulator these valves are used for HEATING. Reverse-Acting valves close with temperature decrease and outward stem motion. On a regulator these valves are used for COOLING.
Operation, Installation & Maintenance Manual Series 38R ••• Self-Acting Temperature Control Valves REVERSING THE VALVE ACTION (continued) Procedure 1. Remove the valve body from the actuator as instructed in “Removing Valve Body Assembly”. 2. Unlock and remove the two stem locknuts. 3. Carefully remove the stem packing. See “Replacing Valve Stem Packing”. Place packing in a safe CLEAN area. 4.
Operation, Installation & Maintenance Manual Series 38R ••• Self-Acting Temperature Control Valves 3 WAY-REGULATORS – Installation & Maintenance The Actuators on these regulators are identical to those previously described and the bulb installation is also identical. These valves require three piping connections and can be used to diverge the flow to either of two outlets, or to converge two inlets into one outlet. Port C is normally closed and Port B closes as temperature increases.
Series 38R ••• Self-Acting Temperature Control Valves Operation, Installation & Maintenance Manual Option 3 “FAIL-SAFE” – Installation & Maintenance The valve body assemblies on these models are identical to those previously described and there is no difference in their servicing. However, the actuators are different and larger bellows are used to develop adequate thrust with the limited pressure differential available below atmospheric pressure.
Operation, Installation & Maintenance Manual Series 38R ••• Self-Acting Temperature Control Valves TYPICAL APPLICATIONS Typical Heat Exchanger Application Using a Self-Op 2-Way Valve HEATING Use an Direct-Acting Valve COOLING Use an Reverse-Acting Valve RETURN TO PROCESS STEAM OR WATER INLET Process Side Influence Side STEAM OR WATER RETURN FROM PROCESS HEAT EXCHANGER Typical Heat Exchanger Application Using a Self-Op 3-Way Diverting Valve HEATING Connect Upper Port (C) to Water / Glycol Return and
Operation, Installation & Maintenance Manual Series 38R ••• Self-Acting Temperature Control Valves TYPICAL APPLICATIONS Typical Heating Application Using a Self-Operating Temperature Regulator Sensor installed directly into Process Vessel using Thermowell Sensor installed directly into tank using Thermowell HOT WATER STORAGE TANK Option 2 Actuator with Direct-Acting Valve STEAM INLET STEAM OR WATER TO TRAP, THEN BOILER Typical Heat Exchanger Application Using a Self-Operating Temperature Regulator S
Operation, Installation & Maintenance Manual Series 38R ••• Self-Acting Temperature Control Valves TROUBLE SHOOTING GUIDE PROBLEM: ERRATIC CONTROL CAUSES CORRECTIONS 1. Bent or binding valve stem. 1. Replace with free running stem. 2. Packing binding valve stem. 2. Replace packing set. 3. Poor bulb location. 3. Relocate bulb to more representative average temperature location or add agitation. 4. Sudden load changes requiring greater capacity than valve size can handle. 4.
Operation, Installation & Maintenance Manual Series 38R ••• Self-Acting Temperature Control Valves TROUBLE SHOOTING GUIDE PROBLEM: TEMPERATURE REMAINS BELOW THE DESIRED CONTROL POINT CAUSES CORRECTIONS 1. Adjusting setting too low. 1. Raise setting. 2. Bulb at hot location. 2. Relocate bulb to more representative average temperature location or add agitation. 3. Stem adjustment too long. 3. Readjust. (See Figure 6) 4. Valve size too small. 4. Replace valve with larger size. 5.
Notes (Adjustments, Stem Dimensions, Maintenance Logs) Page 22
Notes (Adjustments, Stem Dimensions, Maintenance Logs) Page 23
Dwyer Instruments Inc. P.O.
