Series 2-5000
Minihelic® II Differential Pressure Gage
Combining clean design, small size and low cost with enough accuracy for all but the most demanding applications our
Minihelic® II gage offers the latest in design features for a dial type differential pressure gage. It is our most compact
gage but is easy to read and can safely operate at total pressures up to 30 psig. The Minihelic® II gage is designed for panel
mounting in a single 2-5/8" diameter hole. Standard pressure connections are barbed fittings for 3/16" I.D. tubing; optional 1/8"
male NPT connections are also available. Over-pressure protection is built into the Minihelic® II gage by means of a blow-out
membrane molded in conjunction with the diaphragm. Accidental over-ranging up to the rated total pressure will not damage the gage.
With removable lens and rear housing, the gage may be easily serviced at minimum cost.
With the housing molded from mineral and glass filled nylon and the lens molded from acrylic, the gage will withstand
rough use and exposure as well as high total pressure. The 5% accuracy and low cost of the Minihelic® II gage make it
well-suited for a wide variety of OEM and user applications. OEM applications include cabinet air purging, medical respiratory
therapy equipment, air samplers, laminar flow hoods, and electronic air cooling systems. As an air filter gage, the
Minihelic® II gage finds many end use applications on large stationary engines, compressors, ventilators, and air handling
units. The Minihelic® II gage is suitable for many of the same applications as the Magnehelic® gage where the greater
accuracy, sensitivity, and higher and lower differential pressure ranges of the Magnehelic® gage are not required.
Printable Literature
Service Manual
Dimensional Drawings
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Series 2000
Magnehelic® Differential Pressure Gage
Select the Magnehelic® gage for high accuracy--guaranteed within 2% of full scale--and for the wide choice of 81 models
available to suit your needs precisely. Using Dwyer's simple, frictionless Magnehelic® gage movement, it quickly indicates
low air or non-corrosive gas pressures--either positive, negative (vacuum) or differential. The design resists shock, vibration
and over-pressures. No manometer fluid to evaporate, freeze or cause toxic or leveling problems. It's inexpensive, too.
The Magnehelic® gage is the industry standard to measure fan and blower pressures, filter resistance, air velocity,
furnace draft, pressure drop across orifice plates, liquid levels with bubbler systems and pressures in fluid amplifier or fluidic
systems. It also checks gas-air ratio controls and automatic valves, and monitors blood and respiratory pressures in medical
care equipment.
Note: May be used with Hydrogen. Order a Buna-N diaphragm. Pressures must be less than 35 psi.
Printable Literature
Service Manual - Series 2000
Service Manual - Series 2000 AF
Service Manual - Series 2000 with HP or MP Option
Dimensional Drawings
Catalog Pages
Series 2000-SP
Magnehelic Differential Pressure Gage
Bright red LED on right of scale shows when setpoint is reached. Field adjustable from gage face, unit operates on 12-24 VDC.
Requires MP or HP style cover and bezel.
Printable Literature
Service Manual
Dimensional Drawings
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Series 4000
Capsuhelic® Differential Pressure Gage
The Capsuhelic® gage is designed to give fast, accurate indication of differential pressures. The gage may
be used as a readout device when measuring flowing fluids, pressure drop across filters, liquid levels in storage
tanks and many other applications involving pressure, vacuum or differential pressure.
Using the basic design
of Dwyer's time-proven Magnehelic® gage, the Capsuhelic® gage contains a simple, frictionless movement that
permits full scale readings as low as 0.5 inch water column. The pressure being measured is held within a capsule
which is an integral part of the gage. This containment of the pressure permits the use of the gage on system
pressures of up to 500 psig, even when differentials to be read are less than 0.1 inch w.c.
The diaphragm-actuated Capsuhelic® gage requires no filling liquid which might limit its outdoor
applications. Zero and range adjustments are made from outside the gage, and there is no need to disassemble
the gage in normal service.
Note: May be used with Hydrogen. Order a Buna-N diaphragm. Pressures must be less than 35 psi.
Printable Literature
Service Manual
Dimensional Drawings
Catalog Pages
Series DM-1000
DigiMag® Digital Differential Pressure and Flow Gages
The DigiMag® Series DM-1000 Digital Differential Pressure and Flow Gages monitor
the pressure of air and compatible gases just as its famous analog predecessor the
Magnehelic® Differential Pressure Gage. All models are factory calibrated to
specific ranges. The 4-digit LCD can display readings in common English and metric
units so conversions are not necessary. The simplified four button operation reduces set
up time and simplifies calibration with its digital push button zero and span.
The DigiMag® Digital Gages are more versatile than analog gages with
their ability to be field-programmed to select pressure, air velocity or flow operation
depending on model. The DigiMag® Digital Gages have an added feature for filter
applications where a set point can be input where the display will blink when the
filter is dirty, alerting the user that a maintenance action needs to occur.
Programming the Series DM-1000 is easy using the menu key to access 4 simplified
menus which provide access to, depending on model: security level; engineering units; K-factor
for use with various Pitot tubes and flow sensors circular or rectangular duct size for volumetric
flow operation; filter set point; view peak and valley process readings; digital damping for
smoothing erratic process applications; display update to conserve battery life; zero and span field calibration.
The Series DM-1000 DigiMag® Digital Differential Pressure and Air Flow Gages possess a
full-scale accuracy of 1% on ranges down to 2" w.c. and 2% accuracy down to the very low range
of 1" to 0.25" w.c. DigiMag® Digital Differential Pressure Gages offer power versatility by
working with 9-24 VDC line power or simply 9V battery power. If using line power and connecting
the 9V battery, the battery will act as a back-up if line power is lost or interrupted.
Printable Literature
Service Manual - DM-1100
Service Manual - DM-1200
Dimensional Drawings
Catalog Pages
Series PTGB
Differential Pressure Piston-Type Gage
The Series PTGB Differential Pressure Piston-Type Gage is a low cost differential pressure gage
used to measure the pressure drop across filters, strainers, pump performance testing, and heat
exchanger pressure drop monitoring. Its simple, rugged and compact design possesses a weather
and corrosion resistant gage front with a shatter resistant lens. The Series PTGB contains a
piston-sensing element, which provides differential pressure ranges from 0-10 psid to 0-110
psid with accuracies of ±3-2-3%. Constructed from aluminum or 316 stainless steel and
available with two 1/4" female NPT back or end connections, the Series PTGB is
cost-effective and accurate in monitoring differential pressure.
Printable Literature
Service Manual
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Series 3000MR/3000MRS
Using solid state technology, the Series 3000MR and 3000MRS
Photohelic® switch/gages combine the functions of a
precise, highly repeatable differential pressure switch with a large easy-to-read analog pressure gage employing the durable,
time-proven Magnehelic® gage design. Switch setting is easy to adjust with large external knobs on the gage face. Gage reading
is unaffected by switch operation - will indicate accurately even if power is interrupted. Solid state design now results in
greatly reduced size and weight. Units can be flush mounted in 4-13/16" (122 mm) hole or surface mounted with hardware supplied.
3000MR models employ versatile electromechanical relays with gold over silver contacts - ideal for dry circuits. For applications
requiring high cycle rates, choose 3000MRS models with SPST (N.O.) solid state relays. All models provide both low and high limit
control and include 18-inch (45 cm) cable assemblies for electrical connections.
Gage accuracy is ±2% of full scale and switch
repeatability is ±1%. Switch deadband is one pointer width - less than 1% of full scale. Compatible with air and other
non-combustible, non-corrosive gases, they can be used in systems with pressures to 25 psig (1.725 bar). Optional construction
is available for use to either 35 psig (2.42 bar) or 80 psig (5.51 bar).
Included Accessories: mounting ring, snap ring; 18"
(45 cm) cable assembly; (2) 3/16" tubing to 1/8" NPT adapters; (2) 1/8" NPT pipe plugs; (4) 6-32 x 1-1/4" RH machine screws
(panel mounting); and (3) 6-32 x 5/16" RH machine screws (surface mounting).
Printable Literature
Service Manual - 3000MR Photohelic®
Service Manual - 3000MRS Photohelic®
Dimensional Drawings
Catalog Pages
Series 3000SGT
Photohelic® Pressure Switch Gage with Integral Transmitter
The Series 3000SGT Photohelic® Switch/Gage/Transmitter combines several critical control functions into a single,
easy-to-install package. This versatile instrument starts with the universally accepted standard for reliable low air
pressure measurement, the Dwyer® Magnehelic® Gage. It measures positive, negative or differential pressures
within ±2% of full scale accuracy. This time-proven component provides highly reliable analog indication of air
or compatible gas pressure on a 4", 80° scale. Gage operation is completely independent - functions normally even
if power is interrupted to electrical elements of the control.
Next, two DPDT relays are added which serve as Low/High limit controls (or pressure switches) capable of
handling up to 10 amps @ 28 VDC or 120/240 VAC directly. Individual set point deadband is one pointer width - less
than 1% of full scale; just enough to assure positive, chatter-free operation. Integral holding coils enable user
to connect the two so they work like a single control with variable deadband - ideal for applications such as
clean room and building pressurization, HVAC systems, automatic air filter or level control and much more.
Actuation points are fully adjustable over the entire pressure range with convenient front mounted knobs
linked to bright red set point indicators.
Finally, the Series 3000SGT Photohelic® Switch/Gage includes
a separate 4-20 mA, 2-wire transmitter operating from an external 10-35 VDC power supply. Separate adjustments
are included for zero and span inside the rear electronics enclosure. Optional A-700 Power Supply is a perfect
companion rated for AC inputs from 100-240V; DC outputs from 24-28V. The transmitter component is an ideal
driver for variable speed blowers and fans, damper positioners and for continuous data logging on computerized
VAV systems or strip chart recorders.
Besides the obvious cost and space saving advantages of combining all
these control functions in a single unit, think of the additional savings in time and material with just one
set of pneumatic lines to connect instead of three or four.
Printable Literature
Service Manual
Dimensional Drawings
Catalog Pages
Series 43000
Capsu-Photohelic® Pressure Switch/Gage
Capsu-Photohelic® Switch/Gages function as versatile, highly repeatable pressure switches combined with
a precise pressure gage employing the time-proven Magnehelic® gage design. The Capsu-Photohelic® switch/gage
employs an encapsulated sensing element for use with both liquids and gases at pressures to 500 psig (34 bar).
Optional cast brass case is available for water or water based liquids. Two phototransistor actuated,
DPDT relays are included for low/high limit control. Easy to adjust set point indicators are controlled by
knobs located on the gage face. Individual set point deadband is one pointer width - less than 1% of full
scale. Set points can be interlocked to provide variable deadband - ideal for control of pumps, etc.
Printable Literature
Service Manual
Dimensional Drawings
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Series A3000
Photohelic® Pressure Switch/Gage
Photohelic® Switch/Gages function as versatile, highly repeatable pressure switches combined with a
precise pressure gage employing the time-proven Magnehelic® gage design. The Photohelic® switch/gage
measures and controls positive, negative or differential pressures of air and compatible gases. Standard models
are rated to 25 psig (1.7 bar) with options to 35 (2.4) or 80 (5.5 bar) psig. Single pressure 36000S models
measure to 6000 psig (413 bar) with a 9000 psig (620 bar) rating. Two phototransistor actuated, DPDT relays
are included for low/high limit control. Easy to adjust set point indicators are controlled by knobs located
on the gage face. Individual set point deadband is one pointer width - less than 1% of full scale. Set points
can be interlocked to provide variable deadband - ideal for control of fans, dampers, etc. Gage reading is
continuous and unaffected by switch operation, even during loss of electrical power. Choose from full scale
pressure ranges from a low 0-.25" (0-6 mm) w.c. up to 30 psi (21 bar); single positive pressure to 6000 psig
(413 bar).
Photohelic Sensing - How It WorksIn typical applications, these Dwyer switch/gages control between
high and low pressure set points. When pressure changes, reaching either set point pressure, the infrared
light to the limiting phototransistor is cut off by the helix-driven light shutter. The resulting phototransistor
signal 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.
Relay-Transformer Features - A plastic housing protects all electronic components. Solid-state
and integrated circuit electronics are on glass-epoxy printed circuit boards and self-extinguishing terminal boards.
Printable Literature
Service Manual - A3000 Photohelic®
Service Manual - 3000 Photohelic®
Dimensional Drawings
Catalog Pages
Series MP
Mini-Photohelic Differential Pressure Switch/Gage
The Series MP Mini-Photohelic® differential pressure switch/gage combines the time proven
Minihelic® II differential pressure gage with two SPDT switching set points. The Mini-Photohelic®
switch/gage is designed to measure and control positive, negative, or differential pressures consisting
of non-combustible and non-corrosive gases. Gage reading is independent of switch operation. Switching
status is visible by LED indicators located on the front and rear of the gage. Set points are adjusted
with push buttons on back of unit. This extremely compact switch/gage is ideal for fume hoods, dust
collection, pneumatic conveying and clean room applications.
Printable Literature
Service Manual
Dimensional Drawings
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Series DH
Digihelic® Differential Pressure Controller
The Series DH Digihelic® Differential Pressure Controller is a 3 in 1 instrument possessing a
digital display gage, control relay switches, and a transmitter with current output. Combining
these 3 features allows the reduction of several instruments with one product, saving inventory,
installation time and money. The Digihelic® controller is the ideal instrument for pressure,
velocity and flow applications, achieving a 0.5% full scale accuracy on ranges from 0.25 to 100 in. w.c.
The Digihelic® controller allows the selection of pressure, velocity or volumetric flow
operation in several commonly used engineering units. Two SPDT control relays with adjustable dead
bands are provided along with a scalable 4-20 mA process output. In velocity of flow modes, a square
root output is provided on the 4-20 mA signal to coincide with the actual flow curve. The Series
DH provides extreme flexibility in power usage by allowing 120/220 VAC and also 24 VDC power which
is often used in control panels.
Programming is easy using the menu key to access 5 simplified menus which provide access
to: security level; selection of pressure, velocity or flow operation; selection of engineering
units; K-factor for use with flow sensors; rectangular or circular duct for inputting area in flow
applications; set point control or set point and alarm operation; alarm operation as a high, low or
high/low alarm; automatic or manual alarm reset; alarm delay; view peak and valley process readings;
digital damping for smoothing erratic process applications; scaling the 4-20 mA process output to
fit your application's range; Modbus® communications; and field calibration.
With all this packed into one product it is easy to see why the Digihelic® controller
is the only instrument you will need for all your pressure applications.
Printable Literature
Service Manual - DH Digihelic®
Service Manual - DH Quick Set-up
Dimensional Drawings
Catalog Pages
Series DHII
Digihelic® II Differential Pressure Controller
The Digihelic® Controller just got better with the New Series DHII Differential Pressure
Controller. The DHII takes all the fabulous features of the standard Digihelic® Pressure
Controller and packages them in a robust NEMA 4 (IP66) housing.
The Digihelic® II Pressure Controller combines the 2 SPDT control relays, 4-20
mA process output and Modbus® communications with a large, brightly backlit 4 digit LCD
display that can easily be seen from long distances. The electrical wiring has also been
enhanced in the DHII with its detachable terminal blocks. The removable terminals allow
the install to easily wire the terminal block outside the housing and then attach to the
circuit board, reducing wiring difficulties and installation time on the process.
The Digihelic® II Differential Pressure Control in the new NEMA 4 (IP66)
enclosure enables this product to be the perfect choice when mounting pressure controls
outdoors in such applications as rooftop air handlers. This housing also makes it the
ideal solution for surface mounting in clean rooms or facilities where water or a
cleaning solution is utilized in maintaining plant cleanliness.
Printable Literature
Service Manual
Dimensional Drawings
Catalog Pages
Series DH3
Digihelic Differential® Pressure Controller
The Series DH3 Digihelic® Differential Pressure Controller is a 3 in 1 instrument possessing a digital
display gage, control relay switches, and a transmitter with current output all packed in the popular
Photohelic® gage style housing. Combining these 3 features allows the reduction of several instruments
with one product, saving inventory, installation time and money. The Digihelic® controller is the ideal
instrument for pressure, velocity and flow applications, achieving a 1% full scale accuracy on
ranges down to the extremely low 0.25" w.c. to 2.5" w.c. full scale. Ranges of 5" w.c. and greater
maintain 0.5% F.S. accuracy. Bi-directional ranges are also available.
The Series DH3 Digihelic®
controller allows the selection of pressure, velocity or volumetric flow operation in several commonly
used engineering units. 2 SPDT control relays with adjustable deadbands are provided along with a
scalable 4-20 mA process output.
Programming is easy using the menu key to access 5 simplified
menus which provide access to: security level; selection of pressure, velocity or flow operation;
selection of engineering units; K-factor for use with flow sensors; rectangular or circular duct
for inputting area in flow applications; set point control or set point and alarm operation;
alarm operation as a high, low or high/low alarm; automatic or manual alarm reset; alarm delay;
view peak and valley process reading; digital damping for smoothing erratic process applications;
scaling the 4-20 mA process output to fit your applications range and field calibration.
Printable Literature
Service Manual
Dimensional Drawings
Catalog Pages
Series 1620
Single and Dual Pressure Switch
Our old faithful switch design is still best where highest precision combined with diaphragm sealed leak proof construction and mounting
simplicity are required. Model 1626 and 1627 differential pressure switches are identical in design and construction except that Model 1626 has a
single electric switch and Model 1627 has dual electric switches. Model 1627 can therefore provide dual control when required. It
can be set to open or close two independent electrical circuits, each preset for its own actuation pressure. Both units have diaphragm
sealed motion take outs providing maximum protection against leakage.
CAUTION: For use only with air or compatible gases.
Printable Literature
Service Manual
Dimensional Drawings
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Series 1630
Large Diaphragm Differential Pressure Switch
Our highest precision conventional large diaphragm pressure switch provides maximum dependability. In addition, it incorporates a
visible set point indicator for maximum convenience. UL and CSA listed, FM approved for general service, these switches are suitable
for most applications in air conditioning and industrial service. Electrical capability of 15 amps handles most small electrical loads.
CAUTION: For use only with air or compatible gases.
Printable Literature
Service Manual
Dimensional Drawings
Catalog Pages
Series 1640
Floating contact Null Switch for High and Low Actuation
The unique electric switch design in the 1640 is another Dwyer Instrument, Inc. innovation. The Dwyer® Model 1640 Differential Pressure
Switch resembles the Series 1630 switches. The Model 1640, however, is equipped with a single pole, double throw floating contact switch
(not snap acting) so it functions as a null switch.
Drawing shows the switching action schematically. As the diaphragm moves in response
to pressure changes, it moves the floating contact to cause switching action at two preset points with no switching action between these points.
The "high" circuit will be closed when rising pressure differential reaches the preset level. The "low" circuit will be closed when falling
pressure differential reaches the preset level.
A typical example of usage is to position motorized dampers when static pressure in a duct
system reaches a desired maximum and reposition the dampers when the static pressure falls to a pre-established minimum. By using a Pitot tube
sensing element the Model 1640 switch can serve in the same way to control air velocity and maintain a constant volume of air in a supply duct.
CAUTION: For use only with air or compatible gases.
Printable Literature
Service Manual
Dimensional Drawings
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Series 1700
Low Differential Pressure Switch Designed for OEM Products
Series 1700 Differential Pressure Switches were specifically designed to satisfy the demands of high volume original equipment manufacturers
for a tough, dependable limit switch at a very low price. The Model 1710 uses Dwyer's simple, time-proven method of mechanically coupling a
sensitive 3" diameter silicone rubber diaphragm to a versatile SPDT snap switch. The switch housing is precision molded of a high strength glass
filled PPO which has excellent dimensional and thermal stability. This unique combination of existing and new technologies enables Dwyer to offer
a limit switch priced less than comparable units without sacrificing performance. Installation is fast and simple with twist and tighten mounting
screw slots, 1/4" quick connect electrical terminals and dual size barbed pressure ports for 1/8" and 3/16" ID vinyl or rubber tubing.
For use with air and other non-combustible, non-corrosive gases, switches are UL and CSA recognized. Two models are offered with field
adjustable ranges from .15 to .55" w.c. and .50 to 7.5" w.c. Units are rated for 2 psig maximum system pressure, temperature limit is 190°F
and weight is only 4 oz.
NOTE: Minimum quantity order is 50 pieces.
Printable Literature
Dimensional Drawings
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Series 1800
Low Differential Pressure Switch for General Industrial Service
Essential for industrial environments, the Series 1800 combines small size and low price with 2% repeatability for enough accuracy for all but
the most demanding applications. Set point adjustment inside the mounting stud permits mounting switch on one side of a wall or panel with
adjustment easily accessible on the opposite side. UL and CSA listed, and FM approved.
CAUTION: For use only with air or compatible gases.
Printable Literature
Service Manual
Dimensional Drawings
Catalog Pages
Series 1900
Compact Low Differential Pressure Switch
Our most popular series combines advanced design and precision construction to make these switches able to perform many of the tasks of larger,
costlier units. Designed for air conditioning service, they also serve many fluidics, refrigeration, oven and dryer applications. For air and
non-combustible compatible gases, Series 1900 switches have set points from 0.07 to 20" w.c. (1.8 to 508 mm). Set point adjustment is easy
with range screw located inside conduit enclosure. Internal location helps prevent tampering. UL, CE and CSA listed, and FM approved.
CAUTION: For use only with air or compatible gases.
Printable Literature
Service Manual
Dimensional Drawings
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Series 1950G
Explosion-proof Differential Pressure Switch
The Model 1950G Explosion-Proof Switch combines the best features of the popular Dwyer® Series 1950 Pressure Switch with the
benefit of natural gas compatibility. Units are rain-tight for outdoor installations, and are UL listed for use in Class I,
Groups A, B, C, & D; Class II, Groups E, F, & G and Class III atmospheres, Directive 94/9/EC (ATEX) Compliant for CE ATEX II 2G
Exd IIB+H2 T6, CSA & FM approved for Class I, Div. 1, Groups B, C, D; Class II, Div. 1, Groups E, F, G and Class III atmospheres
IECEx Ex d IIB+H2 T6 (-40°C < Ta < +60°C). The 1950G is very compact, about half the weight and bulk of equivalent conventional
explosion-proof switches.
Easy access to the SPDT relay and power supply terminals is provided by removing the top plate of the
aluminum housing. A supply voltage of 24 VDC, 120 or 240 VAC is required. A captive screw allows the cover to swing aside while
remaining attached to the unit. Adjustment to the set point of the switch can be made without disassembly of the housing.
Printable Literature
Service Manual
Dimensional Drawings
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1996 Gas Pressure Switch
Reliable and convenient, the 1996-5 and 1996-20 Gas Pressure Switches serve as a compact, low cost switch for gas fired
furnaces and equipment. Pressure ranges for both models are ideal for high or low gas pressure interlock. Visible set point
and on-off indicators add convenience in servicing. Use either NO or NC contacts on SPDT switch. Bottom connection has both 1/8"
female and 1/4" male threads for pipe nipple or coupling. Top connection vents diaphragm chamber to outside or to furnace
combustion chamber. Mount switch with diaphragm in a horizontal position and gas pressure connection at bottom. Used with natural,
manufactured or LP gas. Also see Model 1950G.
Printable Literature
Service Manual
Dimensional Drawings
Catalog Pages
Series ADPS
HAVC Differential Pressure Switch
The Series ADPS Adjustable Differential Pressure Switch is designed for pressure, vacuum, and differential
pressures. The dual scaled adjustment knob in inches water column and Pascals allows changes to the switching
pressure to be made without a pressure gage. The ADPS is available with settings from 0.08" w.c. (20 Pa) up to
16" w.c. (4000 Pa). The silicone diaphragm and PA 6.6 body make the series ADPS ideal for use with air and other
noncombustible gases. The compact size, adjustment knob and low cost make the ADPS the perfect choice for HVAC applications.
Printable Literature
Service Manual
Dimensional Drawings
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Series BYDS
Bypass Damper Switch
The Series BYDS Bypass Damper Switch is designed to control motorized bypass dampers. As individual zone dampers
open and close, the system static pressure will rise and fall. In order to maintain proper airflow and static pressure
through the HVAC system, a bypass system incorporating a floating type motorized damper and a static pressure control
should be incorporated. A typical on/off pressure switch cannot operate in this application due to the high cycle rate
that would result, eventually causing contact burnout. The BYDS static pressure control is equipped with a solid-state
switching and timing circuit to enhance operation and improve long-term reliability in this demanding application.
Control Operation
The BYDS Bypass Damper Switch is designed for use with a three wire floating point damper actuator used to
control the static pressure on zone control systems requiring motorized bypass dampers. A bypass damper, bypasses
air from the discharge air side of the HVAC unit back in the return air side. The air flow is modulated in order
to maintain a constant static pressure in the system as individual zone dampers open and close. The static pressure
control is equipped with solid-state switching which dramatically increases the life of the control. On an increase
in static pressure the BYDS will send 24 volts out and start the actuator to drive open. When the static pressure
reaches set-point the actuator will stop. After a ten second delay the actuator will start to drive the damper
closed if there has not been an increase in static pressure. A green LED indicates when the damper is in the open
position or being driven open. A 24 VAC transformer is required to power the BYDS control and damper actuator.
The unit includes tubing and two static pressure probes.
Printable Literature
Service Manual
Dimensional Drawings
Catalog Pages
Series H3
Explosion-Proof Differential Pressure Switch
The Series DH3 Digihelic® Differential Pressure Controller is a 3 in 1 instrument
possessing a digital display gage, control relay switches, and a transmitter with current
output all packed in the popular Photohelic® gage style housing. Combining these 3
features allows the reduction of several instruments with one product, saving inventory,
installation time and money. The Digihelic® controller is the ideal instrument for pressure,
velocity and flow applications, achieving a 1% full scale accuracy on ranges down to the extremely
low 0.25" w.c. to 2.5" w.c. full scale. Ranges of 5" w.c. and greater maintain 0.5% F.S. accuracy.
Bi-directional ranges are also available.
The Series DH3 Digihelic® controller allows the selection of pressure, velocity or
volumetric flow operation in several commonly used engineering units. 2 SPDT control relays with
adjustable deadbands are provided along with a scalable 4-20 mA process output.
Programming is easy using the menu key to access 5 simplified menus which provide
access to: security level; selection of pressure, velocity or flow operation; selection
of engineering units; K-factor for use with flow sensors; rectangular or circular duct
for inputting area in flow applications; set point control or set point and alarm operation;
alarm operation as a high, low or high/low alarm; automatic or manual alarm reset; alarm delay;
view peak and valley process reading; digital damping for smoothing erratic process applications;
scaling the 4-20 mA process output to fit your applications range and field calibration.
Printable Literature
Service Manual
Dimensional Drawings
Catalog Pages
Series 3100D
Explosion-proof Differential Pressure Transmitter
The Mercoid® Series 3100D Smart Pressure Transmitter is a microprocessor-based high performance transmitter,
which has flexible pressure calibration, push button configuration, and programmable using HART® Communication.
The Series 3100 is capable of being configured for differential pressure or level applications with the zero and
span buttons. A field calibrator is not required for configuration. The transmitter software compensates for
thermal effects, improving performance. EEPROM stores configuration settings and stores sensor correction
coefficients in the event of shutdowns or power loss. The Series 3100 is FM approved for use in hazardous
(classified) locations. The 100:1 rangeability allows the smart transmitter to be configured to fit any application.
Printable Literature
Service Manual
Dimensional Drawings
Catalog Pages
Series 603A
Differential Pressure Indicating Transmitter
The Series 603A Differential Pressure Transmitters combine ultra low ranges, low cost, high accuracy and rugged
construction - ideal for a wide range of HVAC and industrial applications. These transmitters provide a standard 4-20 mA analog
output signal in ranges as low as 0.2" w.c.
The transmitter can be surface mounted or flush mounted in a 4-13/16" (122 mm) diameter
panel hole. Hardware is included for either option. Duplicate 1/8" female NPT pressure connections on side and back ease installation.
Printable Literature
Service Manual
Dimensional Drawings
Catalog Pages
Series 604D
Minihelic® Differential Pressure Indicating Transmitter
The Series 604D Minihelic® differential pressure Indicating Transmitter combines visual monitoring with electronic control
of low differential air or compatible gas pressures. This versatile device is ideal for building HVAC systems where local
indication is needed during maintenance checks or when troubleshooting the system. The transmitter design employs the latest
strain gage technology and operates in 2-wire control loop circuits. Separate Zero and Span controls plus a 4-screw terminal
strip are protected in a gasketed side enclosure. Cable gland fits .10-.25" round cable. A 10-35 VDC power supply is required.
Printable Literature
Service Manual
Dimensional Drawings
Catalog Pages
Series 605
Magnehilc® Differential Pressure Indicating Transmitter
The Series 605 Magnehelic® Indicating Transmitter provides for both visual monitoring and electronic control of very
low differential pressure. The Series 605 is ideal for control applications in building HVAC systems where local indication is
desired during routine maintenance checks or necessary when trouble shooting the system. The easily read dial gage is complimented
by the two-wire, 4-20 mA control signal utilizing the time-proven Dwyer® Magnehelic® gage mechanical design and Series 600
transmitter technology. The two-wire design with terminal strip on the rear simplifies connection in any 4-20 mA control loop powered
by a 10-35 VDC supply.
Printable Literature
Service Manual
Dimensional Drawings
Catalog Pages
Series 631B
Wet/Wet Differential Pressure Transmitter
The Dwyer Series 631B Differential Pressure Transmitter monitors differential pressure of air and compatible gases and liquids
with accuracy. The design employs converting pressure changes into a standard 4-20 mA output signal for two wire circuits. Digital
push-button, zero and span adjustments are easily accessed on the front cover. The Series 631 Differential Pressure Transmitter is
designed to meet NEMA 4X (IP66) construction. Robust housing offers 500 psi static pressure rating on ranges down to 0.5" w.c.
Printable Literature
Service Manual
Dimensional Drawings
Catalog Pages
Series 636D
Fixed Range Differential Pressure Transmitter
The Series 636D Differential Pressure Transmitter can be used for measuring pressures of liquids, gases & vapors. All available
ranges have an excellent 0.5% F.S. accuracy with a 4-20 mA Output standard or optional 1-5 VDC output. The NEMA 4 housing is an all
316 welded construction that is designed to withstand the harshest environmental conditions. With all 316L wetted materials,
this transmitter is compatible with most media. These units are CSA approved explosion-proof for use in the specified hazardous
locations and meet NACE standards for off-shore applications.
Printable Literature
Service Manual
Dimensional Drawings
Catalog Pages
Series 655A
316 Wet/Wet Differential Pressure Switch
Series 655A Differential Pressure Transmitters are designed for high static/low DP applications designed especially for the
End Users and OEM's where extreme overpressure and high performance of 0.25% accuracy and stability are required at ranges
down to 3" w.c.
Every 655A Series is built using advanced manufacturing techniques to ensure symmetry between the HI and
LO ports. Symmetry, along with automated welding procedures give these differential pressure transmitters excellent performance
and reliability over time at high elevated line pressure. Each unit includes a 6-point N.I.S.T certificate of calibration which
demonstrates the unit's high level of performance.
The 655A Series transmitter pressure ports that are all welded 316 SS with
an O-Ring free design making it ideal for high cyclical applications, capillary filled systems, or applications where a guaranteed
leak free system is needed.
Printable Literature
Service Manual
Dimensional Drawings
Catalog Pages
Series DM-2000
Differential Pressure Transmitter
The Dwyer Series DM-2000 Differential Pressure Transmitter senses the pressure of air and
compatible gases and sends a standard 4-20 mA output signal. The DM-2000 housing is specifically
designed to mount in the same diameter cutout as a standard Magnehelic® gage.
A wide range of models are available factory calibrated to specific ranges.
Pressure connections are inherent to the glass filled plastic molded housing
making installation quick and easy. Digital push-button zero and span simplify calibration
over typical turn-potentiometers. An optional 3.5 digit LCD shows process and engineering
units. A single bush button allows field selection of 4 to 6 engineering units depending on range on LCD models.
Printable Literature
Service Manual
Dimensional Drawings
Catalog Pages
Series 3200G
Explosion proof Pressure Transmitter
The Mercoid® Series 3200G Smart Pressure Transmitter is a microprocessor-based high performance
transmitter, which has flexible pressure calibration, push button configuration, and programmable using HART®
Communication. The Series 3200G is capable of being configured with the zero and span buttons, a field calibrator
is not required for configuration. The transmitter software compensates for thermal effects, improving performance.
EEPROM stores configuration settings and stores sensor correction coefficients in the event of shutdowns or power loss.
The Series 3200G is FM approved for use in hazardous (Classified) locations. The 100:1 rangeability allows the smart
transmitter to be configured to fit any application.
Printable Literature
Service Manual
Dimensional Drawings
Catalog Pages
Series MS
Magnesense® Differential Pressure Transmitter
The Series MS Magnesense® Differential Pressure Transmitter is an extremely versatile transmitter
for monitoring pressure and air velocity. This compact package is loaded with features such as: field
selectable English or metric ranges, field upgradeable LCD display, adjustable dampening of output
signal (with optional display) and the ability to select a square root output for use with Pitot tubes
and other similar flow sensors.
Along with these features, the magnetic sensing technology provides exceptional long term
performance and enables the Magnesense® transmitter to be the solution for a myriad of pressure and flow applications.
Printable Literature
Service Manual - ranges 10" and up
Service Manual - ranges lower than 10"
Dimensional Drawings - Duct Mount
Dimensional Drawings - Wall Mount
Dimensional Drawings - DIN Bracket
Catalog Pages
Series 2-5000
Minihelic® II Differential Pressure Gage
Combining clean design, small size and low cost with enough accuracy for all
but the most demanding applications our Minihelic® II gage offers the latest
in design features for a dial type differential pressure gage. It is our most
compact gage but is easy to read and can safely operate at total pressures up
to 30 psig. The Minihelic® II gage is designed for panel mounting in a
single 2-5/8" diameter hole. Standard pressure connections are barbed fittings
for 3/16" I.D. tubing; optional 1/8" male NPT connections are also available.
Over-pressure protection is built into the Minihelic® II gage by means of
a blow-out membrane molded in conjunction with the diaphragm. Accidental
over-ranging up to the rated total pressure will not damage the gage.
With removable lens and rear housing, the gage may be easily serviced at
minimum cost.
With the housing molded from mineral and glass filled nylon and
the lens molded from acrylic, the gage will withstand rough use and exposure
as well as high total pressure. The 5% accuracy and low cost of the Minihelic® II
gage make it well-suited for a wide variety of OEM and user applications. OEM applications
include cabinet air purging, medical respiratory therapy equipment, air samplers, laminar
flow hoods, and electronic air cooling systems. As an air filter gage, the Minihelic® II
gage finds many end use applications on large stationary engines, compressors, ventilators, and air
handling units. The Minihelic® II gage is suitable for many of the same applications as the
Magnehelic® gage where the greater accuracy, sensitivity, and higher and lower differential
pressure ranges of the Magnehelic® gage are not required.
Printable Literature
Service Manual
Dimensional Drawings
Catalog Pages
