Series 668 Differential Pressure Transmitter
Contents
1. Our low cost Series 668 Differential Pressure Transmitter is capa ble of measuring low pressures with a 1 accuracy ideally suit ed for proper building pressurization and air flow control Transmitters can withstand up to 10 psig overpressure with no damage to the unit Variable capacitance sensor design provides excellent sensitivity and long term stability Compact lightweight design makes installation simple and easy Units also feature reverse polarity protection INSTALLATION Mounting The 668 Series is designed for mounting in either a switch box or by using the two 2 holes that are provided on the housing Optimum performance is obtained by isolating the instrument from vibration and providing relatively clean dry ambient air to the pres sure ports In most cases preferred installation is with the base plate mounted vertically and located on a relatively flat surface in a junction box or attached to a nearby beam CAUTION The axis most sensitive to vibration is the one perpen dicular to the mounting base Avoid mounting with maximum vibration along the axis Pressure Fitting Two 2 3 16 O D pressure fittings are supplied for pressure con nection with 1 4 push on tubing Both the positive high pressure port and the reference low pressure port are located on the top face of the unit labeled High and Low respectively For best results shortest response times 3 16 I D tubing is suggested for tubing lengt2. hs up to 100 feet long 1 4 I D for tubing lengths up to 300 feet and 3 8 I D for tubing lengths up to 900 feet DWYER INSTRUMENTS INC P O Box 373 Michigan City IN 46361 U S A Series 668 Differential Pressure Transmitter Specifications Installation and Operating Instructions 3 1 2 88 90 Bulletin A 30 668 5 32 3 97 MOUNTING HOLE 3 16 4 76 TYP 2 PLACES FITTING 4 1 25 40 T _1 41 64 6 32 SCREW 41 67 W TERMINAL WASHER 1 7 8 47 63 SPECIFICATIONS Service Air and non conductive gases Accuracy 1 of full scale RSS includes non linearity hysteresis and non repeatability Temperature Limits Operating O to 150 F 18 to 65 C Storage 40 to 185 F 40 to 85 C Pressure Limits 10 psig 0 7 kg cm Compensated Temperature Range O to 150 F 18 to 65 C Thermal Effects 0 033 FS F 0 018 FS C Supply Voltage 12 30 VDC Output 4 to 20 mA 2 wire Zero and Span Adjust 1 mA non interactive Response Time lt 60 msec Loop Resistance 0 800 ohms Electrical Connection Terminal strip Pressure Connection 3 16 O D fitting for 1 4 D tubing Housing Fire retardant glass filled polyester Weight 3 oz 85 g Agency Approvals CE Models amp Ranges Model Model O to 0 25 in w c O to 0 5 in w c O to 1 in w c O to 2 5 in W C O to 5 0 in w c O to 10 in w c O to 25 in w c O to 50 in w c O to 100 in w c Bi D
3. irectional Models Model Model O to 0 1 in w c O to 2 5 in W C O to 5 in w c O to 10 In w c O to 25 In w c O to 50 in w c O to 0 25 in w c O to 0 5 in w c O to 1 in w c Also available with optional conduit cover To order add C to part number i e 668C 1 Consult factory for additional information Phone 219 879 8000 Fax 219 872 9057 www dwyer inst com e mail info dwyer inst com ELECTRICAL CONNECTIONS The Series 668 Differential Pressure Transmitter is a loop powered 4 to 20 mA current output unit The current flows into EXC ter minal and returns back to the power supply through the EXC ter minal the power supply must be a DC voltage source with a volt age range between 12 and 30 VDC measured between terminal EXC and EXC The unit is calibrated at the factory using a 250 ohm load at 28 VDC Notes Minimum Supply Voltage VDC 12 0 02 x resistance of receiv er plus line Maximum Supply Voltage VDC 30 0 004 x resistance of receiver plus line CALIBRATION The 668 series is factory calibrated and should require no field adjustment However both zero and span adjustments are pro vided Whenever possible any zero and or span offsets should be corrected by software adjustment in the user s control system Use the zero and span adjustments on the 668 Series only if absolutely necessary The 668 series is calibrated in the vertical position at the fac
4. repairable and should be returned if recalibration or other service is required Contact customer service to obtain an RGA number Please include a clear description of the problem plus any appli cation information available FR R1 443095 00 Rev 1 Phone 219 879 8000 Fax 219 872 9057 www dwyer inst com e mail info dwyer inst com
5. tory For use in other orientations position the unit and follow the zero adjustment procedure listed below Pressure ranges are fixed and cannot be changed in the field Zero Adjustment While monitoring the current output with both pressure ports open to atmosphere the zero may be adjusted For unidirectional pres sure ranges turn the zero adjustment screw until a reading of 4 mA 0 15 mA is achieved Copyright 2004 Dwyer Instruments Inc DWYER INSTRUMENTS INC P O Box 373 Michigan City IN 46361 U S A Printed in U S A 11 04 Span Adjustment Complete the zero adjustment before setting span Span on full scale output adjustments should only be performed by using an accurate pressure standard electronic manometer digital pressure gage etc with at least comparable accuracy to the 668 series lt 1 full scale With full scale pressure applied to the high pressure port reference port open to atmosphere adjust span to achieve 20 mA output Example 1 Unidirectional pressure range of O to 1 w c Apply 1 00 w c adjust soan to 20 mA Notes The input is reverse voltage protected The output is inter nally protected against damage is shorted to ground Recheck all connections before applying power MAINTENANCE After final installation of the Series 668 Differential Pressure Transmitter no routine maintenance is required A periodic check of system calibration is recommended These devices are not field
Download Pdf Manuals
Related Search