Dwyer 3000 User Manual [en, es]

Series 3000 Photohelic®Pressure Switch/Gage

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]

FACE

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

Specifications - Installation and Operating Instructions

Fig. 1

Bulletin B-33

The Photohelic®Switch/Gage is a very versatile, precise pressure

switch combined with the time-proven Magnehelic®pressure gage.
Models are available with one or two phototransistor actuated relays.
Gage reading is unaffected by switch operation. Easy to adjust set points
have knob controls. Applied pressure and switch set points are fully
visible at all times. Deadband is one pointer width - less than 1% of full
scale. Double-pole double-throw relays can be easily interlocked to
provide variable deadband control. For positive, negative or differential
pressure only on 3600S models. Full scale ranges available from 0-.25
in w.c. to 0-6000 psig.

PHOTOHELIC®GAGE SENSING - HOW IT WORKS

In a typical control application, the Photohelic®switch/gage controls
between high and low pressure set points. When pressure changes,
reaching either set point pressure, the beam from an LED to the limiting
phototransistor will be cut off by the helix-driven light shield. The
resulting signal change is electronically amplified to actuate its DPDT
slave relay and switching occurs. Dead band between make and break
is 1% of full scale or less - just enough to assure positive, chatter-free
operation.

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.
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.
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.

DWYER INSTRUMENTS, INC.

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46361, U.S.A. Fax: [phone] e-mail: [e-mail]

Phone: [phone] www.dwyer-inst.com

Bulletin B-33

SNAP RING GROOVE

4-13/16˝ (122 mm)

DIA. HOLE REQUIRED

FOR PANEL MOUNTING

1/8˝ MALE NPT PRESSURE CONNECTIONS.

SINGLE HIGH PRESSURE CONNECTION

FOR SERIES 36000A MODELS.

page 2

INSTALLATION

1. Location

All parts of the Dwyer®Photohelic®pressure switch/gage are ruggedly
constructed and will stand a moderate amount of vibration, physical
shock, and handling. Normal care in handling and installation is all that
is required. In cases where instrument panel vibration is severe, the
panel should be a spring mounted or the amplifier-relay unit mounted
remotely on a more stable surface.

Select a location where the ambient temperature will not exceed 120°F.
Pneumatic pressure sensing lines may be run any necessary distance.
For example, 250 foot sensing lines will not affect accuracy but will damp
the reading slightly. Do not restrict lines. If pulsating pressure or vibration
causes excessive pointer oscillation or relay chatter, consult factory for
additional damping means.

2. Position

The Photohelic

®

Pressure Switch/Gage may be mounted as an integral
package or the amplifier-load relay assembly and housing may be
mounted remotely from the indicating gage-phototransistor unit.
Extension cords with 7 pin plugs and receptacles are available from
Dwyer for interconnection of the two units.

The unit may be mounted in any desired position, scale vertical or
horizontal, without affecting its accuracy, but must be rezeroed if position
is changed from horizontal to vertical or vice versa. The -0 and -00
models must be mounted with the scale vertical.

3. Mounting

The Photohelic

®

Switch/Gage is normally mounted before making
electrical connections, as the electrical enclosure is independent of the
mounting means and may be removed at any time.

Panel Mounting

Normal mounting is flush or through panel is shown in Fig. 2. Be sure to
allow 4-3/8˝ extra space behind the unit for electrical enclosure removal.
Make a single 4-13/16˝ diameter hole in the panel. Insert the entire
Photohelic®Switch/Gage unit from the front, then slip on the mounting
ring and snap ring from the rear. Seat the snap ring in its groove, back
up the mounting ring against snap ring and tighten the four (4) 2˝ No. 6­32 clamp screws provided. If behind panel space is critical, the amplifier­relay unit can be mounted remotely. See the Remote-Relay Mounting
Instructions for details.

Through Panel Mounting

Fig. 2

Gage Mounting with Relays Remote

4-9/32

[108.74]

5

[127.00] SQ

4-9/32

[108.74]

Ø3/16

TYP 4 PLACES

1-1/8

[28.58]

1-1/8

[28.58]

THREE 3/16 DIA.
HOLES AT 120°
SURFACE MTG.

3/4 DIA. HOLE
FOR WIRE CONN.



Where it is desirable to mount the amplifier-relay unit separate from the
gage-phototransistor unit, the gage may be mounted either as shown in
Fig. 2 (except less amplifier-relay portion) or surface mounted as shown
in Fig. 3A. Use the layout shown in Fig. 3B to locate holes. The complete
package cannot be surface mounted.

Surface Mounting

Fig. 3A

Bulletin B-33

page 3

Remote Amplifier-Relay Unit

Fig. 4A

Hole Layout

Hole Layout (Front)

Fig. 3B

Remote Relays Mounting

The amplifier - relay unit may be mounted remotely as shown in Fig. 4A.
Use the hole layout as shown in Fig. 4B for this option.
Additional mounting information for special requirements is available
from the factory.

Fig. 4B

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 adaptors at the Dwyer

®

. Photohelic
pressure/switch gage. Adaptors for rubber or soft plastic tubing are
furnished with the instrument for use where this type of connection is
preferred.

®

If the Photohelic
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

Switch/Gage is not used to sense differential pressure,

®

. No.
A-331 Filter 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 conditions.

Bulletin B-33

4-3/8 [111.13]



COVER MOUNTING SCREWS

SUPPORT CONDUIT
FROM PANEL

COVER PULL

OUT

FLEXIBLE CONDUIT



SECTION B SECTION C

SECTION A

SECTION D

SECTION E

CIRCUIT:
POWER SUPPLY: 
CONTACT RATING: 

page 4

ELECTRICAL CONNECTIONS

1. Cover

The amplifier-relay unit has an easy to remove housing. Remove the
three (3) screws as shown in Fig. 5 and slide the housing off. Make all
the electrical connections before reinstalling and refastening the
housing.

2. Conduit

Electrical access to the connection box portion of the relay housing is by
bottom opening for 3/4˝ conduit. Use of flexible conduit is recommended.
It should be supported from the panel or other suitable surface to prevent
the wiring system from exerting undue strain on the instrument. See Fig.

5.

Mounting Details

Terminal Board

CAUTION: Do not apply electrical

current to terminals in sections B and C.

Fig. 6

Separate Ground Wire attachment is provided for by a No. 6-32 screw

on the mounting bracket near the conduit opening. An additional ground
wire connection is located on the side of the gage body for use when the
amplifier-relay unit is mounted remotely.

Single Set-Point instruments are furnished with the right or high set­point components and circuitry in place. These are connected to
Sections A and B of the terminal board. The left or low set-point
components are omitted.

Fig. 5

3. Terminal or Connection Board Layout

In Fig. 6,”Terminal Board”, Section A contains the connections for the
load or slave relay actuated by the high or right set-point. This relay is a
double pole, double throw type. The two top connections are normally
closed, the two middle connections are normally open, and the bottom
connections are the common pair. The relay is in its normal or De­Energized position when pressure is below the right hand set-point.

Section D is exactly the same as Section A except that its load or slave
relay is controlled by the low or left set-point. The De-Energized position
is below the left hand pointer set-point.

Section B contains the external connections to the holding coil circuit for
the high or right set-point relay and Section C contains similar
connections for the low or left set-point relay. The function and use of
these connections varies somewhat depending on the circuit style of the
instrument. See paragraphs 5 and 6 for details.

Section E contains the power connections for the control unit
transformer primary. The transformer in turn supplies reduced voltage
power for the LED, phototransistor, amplifier unit, and load relay pull in
and holding coils. Connections must always be made to this section in
order to put the unit in operation. Standard units are designed for 117
VAC input to the transformer. Special units are also available for other
voltages.

4. Circuit Style

The Photohelic

®

Switch/Gage is available with several factory installed
optional internal circuits. They are identified as to style by a label shown
in Fig. 7. This label is mounted prominently on the terminal board of each
instrument. The letter H denotes a circuit in which the relay can be made
to latch or remain energized after pressure increase to its set-point.

Circuit Label

Fig. 7

The letter “L” denotes a circuit in which the relay can be made to latch or
remain de-energized after pressure decrease to its set-point. Two letters
are required to fully identify a dual set-point unit. Thus, circuit style HH,
which is standard, is a dual set-point circuit which has provisions for
latching on pressure increase to either set-point. Single relay units are
identified by the letters “SR” followed by “H” for the standard unit or “L”
for the special low latch unit. Units for use with other than standard 117
VAC will be so indicated on the label.