The PHOTOHELIC
®
Series 3000 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 pos-
itive, negative or differential pressure of air or other non-com-
bustible, 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 indepen-
dently, 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: Model No’s. 3020SGT & 3030SGT —
11psi (75 kPa); all other units 5psi (35 kPa).
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-corro-
sive gases
Weight: 4lbs., 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 Fig. B. Allow 4-3/8˝ space behind the unit for elec-
trical enclosure removal. Make 4-3/4˝ diameter hole in panel.
When installing multiple units, it may be preferred to obtain a
Model 730E, 120mm chassis punch as manufactured by
Greenlee Tool Co. and available from your machine tool dis-
tributor.
Insert PHOTOHELIC
®
unit from front of panel, slip the mount-
ing ring over the case from rear and seat the snap ring in its
groove. Thread the (4) 6-32x2˝ machine screws into mount-
ing 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
Fig. A
Fig. B
SNAP RING GROOVE
Ø4-3/4 [120.65]
MOUNTING HOLE
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
Northeast Controls Incorporated
P.O. Box 275 - Upper Saddle River, New Jersey 07458 USA
Tel: 201-327-7660 | Fax: 201-327-3242 | [email protected]
