Bulletin AFS405.011 Distributed by: Cleveland Controls Division of UniControl Inc. 111Brookpark RoadïCleveland OH 44109 TEL: (216) 398-0330ïFAX: (216) 398-8558 Model AFSñ405 Gold Contact Air PressureSensing Switch with Adjustable Set Point Range Dimensions in Inches (Millimeters) Application The Model AFS-405 is a general pur- pose proving switch with gold con- tacts designed for HVAC, Energy Management and DDC (Direct Digi- tal Control) applications. Gold-con- tact switches are commonly used in computer environments, direct digi- tal control, or wherever low ampere currents are wired. It may be used to sense positive, negative, or differen- tial air pressure. General Description & Operation The plated housing contains a dia- phragm, a calibration spring and a snap-acting SPDT switch with gold contacts.The sample connections lo- cated on each side of the diaphragm accept º" OD metallic tubing via the integral compression ferrule and nut.An enclosure cover guards against accidental contact with the live switch terminal screws and the set point adjusting screw. The enclo- sure cover will accept a Ω" conduit connection. Cleveland Controls Division of UniControl Inc. (Figure 2)(Figure 1) tubing is available: order part num- ber 18311. Locate the sampling probe a minimum of 1.5 duct diameters downstream from the air source. In- stall the sampling probe as close to the center of the airstream as possible. Refer to Figure 2 to identify the high pressure inlet (H) and the low pres- sure inlet (L). Select one of the five application options listed below, and connect the sample lines as recom- mended. Mounting (see Figure 1) Select a mounting location which is free from vibration. The AFS-405 must be mounted with the diaphragm in any vertical plane in order to ob- tain the lowest specified operating set point. Avoid mounting with the sample line connections in the ìupî position. Surface mount via the two 3/ 16 " diameter holes in the integral mounting bracket. The mounting holes are 3-7/ 8 " apart. Air Sampling Connection (see Figure 2) The AFS-405 is designed to accept firm-wall sample lines of º" OD tub- ing by means of ferrule and nut com- pression connections. For sample lines of up to 10 feet, º" OD tubing is acceptable. For lines up to 20 feet, use º" ID tubing. For lines up to 60 feet, use Ω" ID tubing. A º" OD adapter, suitable for slip-on flexibleBulletin AFS405.012 Specifications Model AFS-405 Air Flow Switch Mounting Position: Mount with the diaphragm in any vertical plane. Set Point Range: 0.05 ± 0.02" w.c. to 12.0"w.c. Field Adjustable ìOperate Rangeî: 0.07"w.c. to 12.0" w.c. Field Adjustable ìRelease Rangeî: 0.04"w.c. to 11.2" w.c. Approximate Switching Differential: Progressive, increasing from 0.02± 0.01 ìw.c. at minimum set point to approxi- mately 0.8 ì w.c. at maximum set point. Measured Media: Air, or combustion by-products that will not degrade silicon. Maximum Pressure: Ω psi (0.03 bar) Operating Temperature Range: -40F to 180F (-40 to 82C) Life: 100,000 cycles minimum at 1/2 psi maximum pressure each cycle and at maximum rated electrical load. Electrical Rating: 300 VA pilot duty at 115 to 277 VAC, 15 amps noninductive to 277 VAC. 10 ma at 5 VDC (applies to dry circuit applications.) Contact Arrangement: SPDT Contact Material: gold Electrical Connections: Screw-type terminals with cup washers. Conduit Opening: 7/8" diameter opening accepts 1/2" conduit. Sample Line Connectors: Male, externally threaded 7/16" 24 UNS 2A thread, complete with nuts and self- aligning ferrules. Sample Line Connections: Connec- tors will accept 1/4" OD rigid or semi- rigid tubing. Approval: UL, CSA, CE Shipping Weight: 1.2 lbs. (Figure 3) TWO POSITIVE SAMPLES: Con- nect the higher positive sample to in- let H. Connect the lower positive sample to inlet L. ONE POSITIVE AND ONE NEGA- TIVE SAMPLE: Connect the posi- tive sample to inlet H. Connect the negative sample to inlet L. Electrical Connections (see Figure 3) Before pressure is applied to the dia- phragm, the switch contacts will be in the normally closed (NC) position. The snap switch has screw top termi- nals with cup washers. Wire alarm and control applications as shown in Figure 4. Field Adjustment The adjustment range of an AFS-405 Air Switch is 0.05±.02" w.c. to 12.0" w.c. To adjust the set point, turn the adjusting screw counterclockwise until motion has stopped. Next, turn the adjusting screw 4 complete turns in a clockwise direction to engage the spring. From this point, the next ten turns will be used for the actual cali- bration. Each full turn represents approximately 1.2" w.c. Please note: To properly cali- brate a Air Switch, a digital manom- eter or other measuring device should be used to confirm the actual set point. Accessories ïP/N 18311 Slip-on º" OD Tubing Adapter, suitable for slipping on flexible plastic tubing.ïSample line probes.ïOrifice plugs (pulsation dampers). Pressure Conversion Table 1" H 2 O = 0.0361 lbs./sq. in. or 0.0735 in. mercury 1" Hg. = 0.491 lbs./sq. in. or 13.6 in. water 1 psi = 27.7 in. water or 2.036 in. mercury POSITIVE PRESSURE ONLY: Connect the sample line to inlet H; inlet L remains open to the atmo- sphere. NEGATIVE PRESSURE ONLY: Connect the sample line to inlet L; inlet H remains open to the atmo- sphere. TWO NEGATIVE SAMPLES: Connect the higher negative sample to inlet L. Connect the lower nega- tive sample to inlet H. (Figure 4) Location of Sample Lines for Typical Applications AFS-405 Sensing Switches are manufactured by Cleveland Controls Div. of UniControl Inc.Next >