Owner's manual

The Series 3000 PHOTOHELIC
®
SGT is a versatile 3-in-1 instrument combining a
time-proven Magnehelic
®
differential pressure gage, low/high limit pressure
switches and a 4-20 mA pressure transmitter. It is designed to measure and control
positive, negative or differential pressure of air or other non-combustible, non-
corrosive gases. Gage reading is unaffected by switch or transmitter operation.
Switch set points are easily adjusted with knobs located on gage face. Applied
pressure and switch set points are fully visible at all times. Deadband is one pointer
width, less than 1% of full scale. Each set point controls a DPDT relay and both can
be interlocked to provide variable deadband control. The 2-wire transmitter
operates independently, driven by a separate external 10-35 VDC power supply.
Separate zero and span potentiometers are provided inside the rear electronics
package for easy field adjustment.
PHYSICAL DATA
Ambient Temperature Range: 20 to 120˚F (-6.7to 49˚C).
Maximum Pressure: 2 psi (13.8 kPa) for ranges up to 5˝ w.c.; 5 psi (35 kPa) for
ranges 6, 10˝ w.c.; 10 psi (69 kPa) for ranges 20, 30˝ w.c.; 25 psi (170 kPa) for
above ranges.
Accuracy: ±2% of full scale at 70˚F (21.1˚C) (3% on -0).
Pressure Connections: 1/8˝ NPT(F).
Case Finish: Baked dark gray epoxy enamel.
Conduit Opening: 3/4˝.
Standard Accessories: (2) 3/16˝ tubing to 1/8˝ NPT brass adapters for rubber or
vinyl tubing, (1) mounting ring. (1) snap ring, (4) 6-32 x 2˝ mounting screws,
instructions.
Compatibility: Use only with air or other non-combustible, non-corrosive gases.
Weight: 4 lb, 12oz (2.15 kg).
ELECTRICAL SPECIFICATIONS (Switches)
Power Supply: 117 VAC.
Current Consumption: 5 watts average.
Contact Rating: 10A @ 24 VDC or 120 VAC, 6A @ 240 VAC.
ELECTRICAL SPECIFICATIONS (Transmitter)
Power Supply: 10.0 to 35 VDC.
Output Signal: 4-20 mA DC, 2-wire (limited at 38 mA).
Loop Resistance: 0-1250 ohms.
Current Consumption: 38 mA DC, maximum.
Span and Zero Adjustment: Multi-turn potentiometers, internally accessible
Thermal Errors: ±1% per 50˚F typical
Warm-Up Time: 10 minutes.
INSTALLATION
1. Location: Select a clean, dry, vibration-free location where ambient
temperatures will be between 20 and 120˚F (-6.7 and 49˚C). Tubing supplying
pressure to the instrument can be practically any length but long runs will
increase response time slightly.
2. Position: The PHOTOHELIC
®
SGT is factory calibrated for use with scale in a
vertical plane. Operation at other angles may affect accuracy and/or require
zero adjustment. Most models can be specially calibrated at the factory for
other positions if specified at time of ordering. Ranges below 1˝ w.c. must be
used only with scale vertical.
3. Mounting: Normal mounting is flush or through panel as shown in Figure B.
Allow 4-3/8˝ space behind the unit for electrical enclosure removal. Make 4-3/4˝
diameter hole in panel. When installing multiple units, it may be preferred to
obtain a Model 730E, 120 mm chassis punch as manufactured by Greenlee
Tool Co. and available from your machine tool distributor.
Insert PHOTOHELIC
®
SGT from front of panel, slip the mounting ring over the
case from rear and seat the snap ring in its groove. Thread the (4) 6-32x2˝
machine screws into mounting ring, back it against snap ring and tighten
screws to back of panel. An alternative to flush mounting is the optional A-371
Surface Mounting Bracket. Unit is mounted in this bracket as described above
and bracket is then surface mounted. Contact factory for details.
SERIES 3000 SGT PHOTOHELIC
®
DIFFERENTIAL PRESSURE SWITCH/GAGE TRANSMITTER
Specifications – Installation and Operating Instructions
Bulletin B-36A
Figure A
1/8 NPT FEMALE PNEUMATIC TAPS
2-1/16
[52.39]
2
[50.80]
PANEL 5/8 [15.88] MAX
1-1/4
[31.75]
3/16
[4.76]
5/8
[15.88]
2-1/2
[63.50]
3-7/8
[98.43]
5-1/8
[130.18]
4-3/8
[111.13]
HOUSING REMOVAL
3/4 [19.05]
CONDUIT OPENING
Ø4-3/4
[120.65]
FLANGE
3-7/8
[98.43] SQ
HOUSING
Ø4
[101.60]
FACE
5
[127.00]
0.D.
BEZEL
5-1/2
[139.70]
O.D.
MOUNTING 
RING
DWYER INSTRUMENTS, INC.
P.O. BOX 373 • MICHIGAN CITY, INDIANA 46361 U.S.A.
Phone: [phone] www.dwyer-inst.com
Fax: [phone] e-mail: [e-mail]
Figure B
SNAP RING GROOVE
Ø4-3/4 [120.65]
MOUNTING HOLE
B-36A:bulletin B-36A 12/13/10 10:18 AM Page 1