Liquid Level Controls

Transcription

1 Series RS High Pressure Sensors & Probes For onductance ctuated ontrols Series RS Sensors Series-RS-X-BR-: NM 4X nclosure For sophisticated multi-level control in tanks, boilers and hydronic systems Remote sensors, which thread into the top of the boiler or tank, are available with, 2, 3, 4 or 5 probes of varying lengths that can easily be cut to desired set points Probe lengths 2-72" (2.5-83cm) in 2" (2.5cm) increments (purchased separately) ontrol, remote sensor and probe(s) must be ordered separately. Order Spacer S-4 when 2 or more probes greater than 36" (94mm) will be used No blow down required Maximum Temperature 406 F (208 ) Maximum Pressure 250 psig (7.6 kg/cm) High Pressure s and Probes RS--BR ; level.7 (.8) RS-2-BR ; 2 levels 3.3 (.5) RS-3-BR ; 3 levels 3.3 (.5) RS-4-BR ; 4 levels 4.0 (.8) RS-5-BR ; 4 levels 4.3 (.95) for non-metallic tanks See page 7 for probe rods. High Pressure Model RS--BR- High Pressure Model RS-2-BR- Model RS-3-BR- High Pressure Model RS-4-BR- Model RS-5-BR- B F D Probe 4 /2" (4mm) through 36" (94mm) B D Nominal to 6 ft. ( cm) B D Nominal to 6 ft. ( cm) B Probe NPT 6 (43) 2 or 3 Probes 2 NPT 2 32 (59.5) 4 or 5 Probes 2 2 NPT (63) 2 NPT 2 NPT 2 NPT D F Probe (6) 4 (32) 3 4 (83) 2 or 3 Probes (98) 4 (02) 4 or 5 Probes 4 (02) 4 (02) RS--HP Series-RS High Pressure : NM nclosure Maximum Temperature 406 F (208 ) Maximum Pressure 250 psig (7.6 kg/cm) For single sensor applications with high-pressure environments. Requires additional probe rod. See page 7. Model RS--HP K N L M RS--HP 7699 High pressure remote sensor 0.5 (.23) Model K L M N RS--HP 3 4 NPT 7 8 (22) 3 (80) (86) 70

2 Sensors High Pressure Series 750B-3 hamber with 3 Probes Series 750B-4 hamber with 4 Probes 4 3/8" () Specifications hamber 4 3/6" (06) NM 4X chamber enclosure and listed Maximum steam pressure 250 psig (7.6 kg/cm 2 ) Designed for use with a remotely mounted controller to make a complete system for level control in a boiler or other vessel. /2 NPT /2" (293) 2 /2" (63) 3 5/6" (59) 8 5/8" (473) NPT 3 5/6" (59) /2 NPT Remote hamber 3 /8" (79) NPT 750B ast iron chamber w/3 probes 26 (.8) 750B ast iron chamber w/4 probes 26 (.8) Probe Rods Stainless steel - Series 36 material PTF coated probe ends provide protection from false signals [available on 24-72" (60-829mm) probes] For use with RS sensors G-2-SS " (60mm) Ground Probe.0 (.5) G-3-SS " (94mm) Ground Probe.5 (.7) G-4-SS " (29mm) Ground Probe 2.0 (.9) G-5-SS " (524mm) Ground Probe 2.5 (.) G-6-SS " (829mm) Ground Probe 3.0 (.4) P- 3 SS " (4mm) Probe 0.5 (.23) P--SS " (305mm) Probe 0.5 (.23) P-2-SS " (60mm) Probe w/ptf.0 (.5) P-3-SS " (94mm) Probe w/ptf.5 (.7) P-4-SS " (29mm) Probe w/ptf 2.0 (.9) P-5-SS " (524mm) Probe w/ptf 2.5 (.) P-6-SS " (829mm) Probe w/ptf 3.0 (.4) PTF oating P-SS Probes G-SS Probes Selecting control according to anticipated use, the sensor should be selected according to the number of probes required. The probe rods are ordered separately according to length needed. The control, sensor and each probe rod must be specified separately, using the appropriate model and part numbers. 7

3 Sensors Low Pressure RS--LP Maximum Water Temperature: 250 F (2 ) Model RS--LP Maximum Water Pressure: 60 psi (.2kg/cm 2 ) Model RS--LP Maximum Steam Pressure: 5 psig (.0 kg/cm 2 ) an be installed in horizontal orientation Model RS--LP D B RS--LP (.4) RS--LP-S 7628 w/short probe 3.0 (.4) B D NPT (22) 3 (80) (70) (86) 72

4 Replacement lectrode ssemblies P-800 Series Low Pressure 3/4 NPT 3/4 NPT Maximum mbient Temperature: 20 F (49 ) Maximum Water Temperature: 250 F (2 ) Maximum Water Pressure: 60 psi (.2 kg/cm 2 ) P-800/SP/P-RB Series P-800-U Model Part ontrol/sensor Rod Weight Number Number Used On Req. lbs. (kg) P PS-800 Series & RS--LP 0.5 (.23) P-RB RB-22, RS--LP-S & RB (.23) P-800-RX PS-800-RX Series 0.5 (.23) P-800-U 3544 PS-800-U Series 0.5 (.23) /2 NPT P-800-RX2 P-750 Series High Pressure Operating Range: Maximum System Pressure: 250 psi Maximum Temperature at lectrode: 406 F (2 ) P-750-LP 3/8 NPT P-750-HP 3/8 NPT Model Part ontrol/sensor Rod Weight Number Number Used On Req. lbs. (kg) P-750-LP P Series X 0.5 (.23) P-750-HP B- & RS-BR Series X 0.5 (.23) ccessories S Spacer 3.0 (.4) use with RS sensors and P&G probes Spacer and ollar 73

5 Location The location of the remote sensor is not limited to mounting on top of a tank. Depending on the application, it may be decided to mount the remote sensor in a stillwell or equalizing line. The following diagrams show typical locations for several applications. Probe Installation ll boiler manufacturers designate the preferred (and sometimes secondary) location for installation of the probe on their boiler. They have determined that this location is above the minimum safe water level and provides the 4" clearance needed to ensure the probe is not grounded. lways install the probe in these locations, especially on a hot water boiler. If installed in other locations on a hot water boiler, this area could be prone to develop an air pocket. Installation in piping external to the boiler on hot water systems has pitfalls. If the probe is too long and touches the wall of the pipe, the circuit is completed and the control thinks there is water in the system. If the water level drops below the level of the probe in this situation, the burner circuit will never be interrupted and a dry-fire could occur. Open tanks or vessels will probably require mounting the remote sensor on a stillwell to dampen the liquids' wave action. Use 3 or 4 perforated plastic drain pipe with a flange to thread connection at the top. The stillwell can rest on the bottom of the tank or be suspended and secured with brackets. The most common problem with installation on hot water systems occurs when installing the probe in copper pipe. The sweat to thread adapters installed could result in the probe not being inserted in the pipe. n air pocket could develop or scale bridging could occur. While an air pocket causes nuisance shutdown of the boiler, scale bridging can result in a dry-fire if the water drops below the level of the probe. lways make sure at least 2 the length of the probe is in the run of the pipe to ensure proper operation. Make sure tip of probe is in pipe with /4" clearance from wall of pipe. If probe is installed too close to boiler wall, an electrical short could occur. Mounting the remote sensor in an equalizing pipe is an alternative to top mounting. The equalizing pipe should be at least a 2 pipe and have a drain valve at the bottom for flushing. 74 If probe is installed with extensions, an air pocket could develop shutting down the boiler. Debris could develop which can cause an electric short, rendering the low water cut-off ineffective.

6 OPRTION ND SLTION conductance-type control will sense liquids up to 60,000 ohms resistivity. It can be used to activate a low level alarm, high level alarm, pumps to fill/drain a tank or any combination thereof. Typical applications include, but are not limited to, cooling towers, storage tanks, water fountains and condensate receivers. The control utilizes the conductivity of a liquid to make or break circuits. Some liquids may be more resistive than the control can sense (above 60,000 ohms). The resistive and conductive properties of a liquid depend on several factors, including the amount of soluble material, temperature of the liquid, and placement of the probes. TDS tester, which can be purchased from a supply house carrying boiler chemicals, is required to accurately measure a liquid's resistivity. Refer to the following charts to determine the resistivity of the liquid in an application. If it is above the 60,000 ohm rating, another type of control will be required. onductivity Values of Water Resistivity onductivity Series Liquid (Ohms/cm) (Micromhos/cm) 250B Water - Deionized 2,000, Water - Distilled 450,000 2 Water - ondensate 8, X Water - hlorinated 5, X Water - Hard/Natural 5, X Water - Sewage 5, X Water - Salt 2, X ontrol Unit For many applications, water is the liquid being sensed. Raw or tap water usually has naturally occurring salts, chlorides and minerals that make it conductive enough to operate the control. ondensate receiver and cooling tower water are also very conductive due to evaporation. Ultrapure water (RO, deionized, demineralized, etc.) is highly resistive and is not able to conduct the current needed to operate the control. onverting Total Dissolved Solids to Resistivity and onductivity Total Dissolved Solids Resistivity onductivity (ppm) (Ohms/cm) (Micromhos/cm) ,000, ,000, ,000, ,000, , , , , ,000 0, ,000 75

7 Valve Series 27-W For commercial and industrial liquid level open tank applications Materials of construction Brass Monel valve seat, PDM disc Maximum pressure 35 psi (2.5 kg/cm 2 ) Maximum supply pressure 00 psi (7 kg/cm 2 ) Minimum liquid temperature 40 F (4.4 ) Maximum liquid temperature 22 F (00 ) Series 27-W D F B B D F NPT 9 6 (40) (73) (27) (29) (62) apacities FDR DISHRG (kg/hr.) lbs./hr. (4990),000 (4536) 0,000 (4082) (3629) (375) (2722) 9,000 8,000 7,000 6,000 Maximum apacity gpm (lpm) BOILR hp (Kilowatts) 22 (83.27) 39 (327) 20 (75.70) 290 (2843) 8 (68.3) 26 (2559) 6 (60.56) 232 (2274) 4 (52.99) 203 (990) 2 (45.42) 74 (706) (2268) 5,000 0 (37.85) 45 (42) (84) 4,000 8 (30.28) 6 (37) (36) 3,000 6 (22.7) 87 (853) (907) 2,000 4 (5.4) 58 (569) (454),000 2 (7.57) 29 (284) (0) 0 0 (0) psi (kg/cm 2 ) (0) (.7) (.4) (2.) (2.8) (3.5) (4.2) (4.9) (5.6) (6.3) (7.0) DIFFRNTIL PRSSUR IN POUNDS PR SQ. IN. (Water pressure less boiler pressure) 27-W Liquid level control 5 (2.3) 0 (0) 76

8 Float ctuated Pneumatic Series PF For the actuation of pneumatic valves or relays in heating, air conditioning and process systems in hazardous or non-hazardous locations Provides an air pressure signal proportional to the liquid level vailable as Direct cting or Reverse cting float operated armature senses the liquid level Switch mechanism is completely sealed from the liquid Two gauges are provided to display the supply and output pressures lternate air connection tappings are provided for greater flexibility in piping Operating range: - 2" (25-5mm) ir pressure Supply 20 psi (.4 kg/cm 2 ) Output 3-5 psi (.2 - kg/cm 2 ) Maximum water temperature 406 F (208 ) Maximum pressure 250 psig (7.6 kg/cm 2 ) Series PF 5" (27mm) Min. learance Required to Remove over B D F G H J K L NPT NPT NPT NPT NPT (78) 8 (203) 3 4 (45) (67) 4 (02) (527) Output K J L H B Supply D G F Water Level djustment Model Type Level djustment Range in. (mm) PF--G Direct cting - 2 (25-5) PF--GR Reverse cting - 2 (25-5) Output ir Proportional Band 00% Operating Range 2" (5mm) 50% " (25mm) Reverse cting Direct cting PF--G Direct acting pneumatic liquid level control 38.5 (7.5) PF--GR 8080 Reverse acting pneumatic liquid level control 38.5 (7.5) psi (kg/cm 2 ) (.2) (.4) (.6) (.8) () Output ir 77