
Bulletin B-33-A
Ø4-13/16 [122.24]
HOLE REQUIRED FOR
PANEL MOUNTING
1/2 NPT(M) PRESSURE CONNECTION.
SINGLE HIGH PRESSURE CONNECTION
FOR SERIES 36000S MODELS.
SNAP RING GROOVE
2-1/2 [63.50]
2-1/16 [52.39]
2 [50.80]
1-1/4
[31.75]
(4) 6-32 HOLES
EQUALLY SPACED ON
A 5-1/8 [130.18] B.C.
Ø4-47/64
[120.25]
Ø5
[127.00]
Ø4 [101.60]
FAC E
5-1/2 [139.70]
O.D.
MOUNTING
RING
5/8 [15.88]
5/8 [15.88] PANEL
MAX
3/16 [4.76]
3-7/8 [98.43]
5-1/8 [130.18]
6-3/8 [161.93]
(7-5/8 [193.68])
4-3/8 [111.13]
HOUSING REMOVAL
3/4 CONDUIT
CONNECTION
Ø4-3/4
[120.65]
3-7/8 SQ
[98.43]
1/8 FEMALE NPT HIGH
PRESSURE CONNECTION
1/8 FEMALE NPT LOW
PRESSURE CONNECTION
Series A3000 Photohelic®Differential Pressure Switch/Gage
Specifications - Installation and Operating Instructions
Fig. A
NOTE: Detailed dimension drawings are available from our Customer Service
Dept. for PHOTOHELIC
For weatherproof housing, request no. 13-700132-00. /For explosion-proof
The PHOTOHELIC®Series A3000 is a versatile 2-in-1 instrument combining a time-proven Magnehelic
®
differential pressure
gage with low/high pressure switches. It is designed to measure
and control positive, negative or differential pressure of air or other
non-combustible, non-corrosive gases. Gage reading is unaffect-
INSTALLATION
1. Location: Select a clean, dry, vibration-free location where
ambient temperatures will be between 20 and 120°F (-6.67 and
48.9°C). Tubing supplying pressure to the instrument can be prac-
tically any length but long runs will increase response time slightly.
ed by switch 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 relays can be interlocked to provide variable deadband
control.
2. Position: The PHOTOHELIC
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.
SPECIFICATIONS
GAGE SPECIFICATIONS
Service: Air and non-combustible, compatible gases.
Wetted Materials: Consult factory.
Accuracy: ±2% of full scale at 70°F (21.1°C). ±3% on -0 and
±4% on -00 models.
Pressure Limits: -20" Hg. to 25 psig (-0.677 to 1.72 bar). MP
option; 35 psig (2.41 bar), HP option; 80 psig (5.52 bar). 36003S
– 36010S; 150 psig (10.34 bar). 36020S and higher;1.2 x full
scale pressure.
Temperature Limits: 20 to 120°F.
(-6.67 to 48.9°C) Low temperature option available.
Process Connections: 1/8˝ female NPT.
3. Mounting: The PHOTOHELIC
making electrical connections. The electrical enclosure is remov-
able at any time regardless of mounting method.
(A) Panel Mounting: Normal mounting is flush or through panel
as shown in Fig. B. Allow 4-
unit for removal of electrical enclosure. Make a 4-13/16˝ (122.24
mm) diameter hole in panel. Insert the PHOTOHELIC
front of panel and slip mounting ring over case from behind with
stepped side facing rear. Fit the snap ring into narrow groove at
back edge of the bezel. Thread four 6-32 x 1-1/4˝ mounting
screws into tapped holes in mounting ring and seat it against snap
ring. Tighten screws against back of panel. See Fig. B.
Size: 4˝ (101.6 mm) dial face, 5˝ (127 mm) O.D. x 8-1/4˝ (209.55
mm).
Weight: 4 lb (1.81 kg).
SWITCH SPECIFICATIONS
Switch Type: Each setpoint has 2 Form C relays (DPDT).
Repeatability: ±1% of full scale.
Electrical Rating: 10A @ 28 VDC, 10A @ 120, 240 VAC.
Electrical Connections: Screw terminals. Use 167°F (75°C)
copper conductors only.
Power Requirements: 120 VAC, 50/60 Hz; 240 VAC & 24 VAC
Power optional.
Mounting Orientation: Diaphragm in vertical position. Consult
factory for other position orientations.
Set Point Adjustment: Adjustable knobs on face.
Agency Approvals: Photohelic
Sec. 4; CSA: File No. LR22541-34; CE: EN 61000-6-2: 1999,
EN 6100-3-2: 2000, EN 61000-3-3: 2000.
DWYER INSTRUMENTS, INC.
P.O. BOX 373 • MICHIGAN CITY, INDIANA 46361, U.S.A. Fax: 219/872-9057 e-mail: info@dwyer-inst.com
®
UL: File No. E38121, Vol. 1,
Phone: 219/879-8000 www.dwyer-inst.com
®
switch/gages as installed in two optional enclosures.
housing, request no. 13-700113-01.
®
Switch/Gage is factory calibrated
®
is normally mounted before
3
/8˝ (111.13 mm) clearance behind the
Fig. B
®
unit from

(B) Surface Mounting with Remote Relays: Where it is pre-
(3) Ø3/16 [4.76] MOUNTING
HOLES EQUALLY SPACED ON A
401/8 [104.78] B.C.
Ø3/4 [19.05] WIRE
CONNECTION HOLE
1-1/8
[25.58]
1-1/8
[28.58]
Ø3/16
TYP 4 PLACES
4-9/32
[108.74]
4-9/32
[108.74]
5
[127.00] SQ
ferred to mount the amplifier-relay unit separate from the gage
assembly, the gage is mounted as shown in Fig. B (without amplifier-relay package) or surface mounted as shown in Fig. C. Use the
dimensions in Fig. D to locate holes.
Fig. C
Fig. E
Fig. D
(C) Remote Relays Mounting: On factory supplied RMR (remote
mounted relay) units, the amplifier-relay package will be furnished
attached to a mounting plate as shown in Fig. E. Use the hole layout in Fig. F for this option. A five foot cable assembly is included
for connecting the two components. Longer cable lengths are
available from the factory.
Fig. F
4. Pneumatic Connections & Zeroing: After installation but
before making pressure connections, set the indicating pointer
exactly on the zero mark, using the zero adjust screw located at
the bottom of the front cover. Note that this adjustment can only
be made with the high and low pressure taps both open to atmosphere.
Connect the high and low pressure taps to positive, negative, or
differential pressure sensing points. Use 1/4˝ diameter metal or
other instrument tubing and 1/8˝ NPT adapters at the PHOTO-
®
HELIC
pressure switch/gage. Adapters for rubber or soft plastic
tubing are furnished with the instrument for use where this type of
connection is preferred.
If the PHOTOHELIC
®
is not used to sense differential pressure, one
of the pressure taps must be left open to atmosphere. This will
allow the reference pressure to enter. In this case, installation of a
Dwyer No. A-331 Filter Vent Plug or similar fitting in the reference
pressure tap is recommended to reduce the possibility of dust
entering the instrument.
NOTE: If the PHOTOHELIC
®
switch/gage is over pressured, pointer may “jump” from full scale back to zero and remain there until
the excess pressure condition is relieved. Users should be aware
of possible false zero pressure indications under this condition.