The Dwyer 3000MRS-60PA is a Series 3000MRS Photohelic® Differential Pressure Switch/Gage — a compact, solid-state-controlled combination differential pressure gage and dual-setpoint switch in a single 4 in dial-face housing. Calibrated for a 0-60 Pa range. Both setpoints (high-limit and low-limit) are independently adjusted with knobs on the gage face and visible at all times alongside the live pressure reading.
The 3000MRS variant uses solid-state relays — 2 SPST N.O. per gage (one per setpoint) with no mechanical contacts to wear. Ideal for high cycle rate applications such as rapid alarm sequencing, equipment cycling, or repetitive process control where electromechanical contact wear would limit service life. Switching voltage 20-280 VAC, current 1.0 A AC max. An 18 in (45 cm) cable assembly with 6-conductor harness and multi-pin connector is included (extension lengths to 100 ft available).
Built on Dwyer's time-proven Magnehelic® gage movement, the 3000MRS reads pressure mechanically — gage indication continues accurately even during loss of electrical power. The compact 3-1/8 in deep housing (only one-third the depth of the standard A3000 Photohelic) and 1.8 lb weight make this an ideal choice for shallow control panels and OEM equipment. Pressure connections are duplicated on both side and back — choose whichever orientation suits your tubing routing. Operates on 24 VDC regulated power.
High-cycle-rate differential pressure alarming where electromechanical contacts would wear out — rapid-cycling alarm sequences, automated test stands, OEM cycling equipment, and any application where switch service life matters. Solid-state relays have no contact bounce, no contact wear, and switching life effectively unlimited. The 0-60 Pa range suits HVAC duct static, filter status, clean room pressurization, and similar pressure alarming applications where high cycling rates are expected.
Key Features
Replaces a pressure gage + two pressure switches in one compact unit. Solid-state SPST N.O. relays — no mechanical contacts to wear out, ideal for high cycle rate applications such as rapid alarm sequencing or automated equipment cycling. Switching voltage 20-280 VAC, 1.0 A AC max.
Solid-state electronics shrink the rear housing to just 3-1/8 in (79 mm) deep and 1.8 lb (816 g) — about one-third the depth and less than half the weight of the standard Dwyer A3000 Photohelic. Fits shallow control panels and OEM equipment where the A3000's 8-1/4 in depth won't clear. 4 in (101.6 mm) dial face remains full-size for easy reading.
The pressure-indicating side of the instrument uses Dwyer's time-proven Magnehelic® mechanical gage movement — the indicator needle is driven directly by the diaphragm with no electronics in the gage path. Pressure reading remains accurate even if 24 VDC power to the switch circuitry is lost. Switch deadband is <1% of full scale (one pointer width).
Two complete sets of 1/8 in female NPT pressure ports — one set on the side, one set on the back of the gage. Use whichever set suits your tubing routing and plug the unused set with the supplied 1/8 in NPT pipe plugs. Reduces installation headaches in tight panels or pre-existing piping setups.
Optional -SS 304 brushed stainless steel bezel has the same installation diameter as a standard Magnehelic® gage — making a field upgrade from a Magnehelic to this Photohelic switch/gage drop-in in existing panel cutouts. No new hole-saw required. Example order code: 3000MRS-60PA-SS.
Operates on regulated 24 VDC (+/-10%) — the standard low-voltage control power used in modern BMS, PLC, and DCS panels. 18 in (45 cm) cable assembly with 6-conductor harness and multi-pin plug included; mates with the rear connector on the gage. Optional extension lengths to 100 ft (30.5 m) available from Dwyer. Recommended R/C snubber (Dwyer A-600) for inductive AC loads.
Technical Specifications
| Specification | Value |
|---|---|
| SKU | 3000MRS-60PA |
| Series | Dwyer Series 3000MRS Photohelic |
| Product Type | Compact Differential Pressure Switch/Gage (Combination) |
| Pressure Range | 0-60 Pa |
| Service | Air and non-combustible, compatible gases |
| Accuracy | +/-4% FS of full scale |
| Repeatability | +/-1% of full scale |
| Deadband | <1% FS (one pointer width) |
| Pressure Limit (Standard) | 25 psig (1.72 bar) |
| Pressure Limit (MP Option) | 35 psig (2.41 bar) |
| Pressure Limit (HP Option) | 80 psig (5.52 bar) |
| Negative Pressure Limit | -20 in Hg (-0.677 bar) |
| Temperature Limits | 20 to 120 deg F (-6.67 to 48.9 deg C); -LT option for use below 20 deg F |
| Process Connections | 1/8 in female NPT, duplicated side and back |
| Switch Type | Solid-state relay per setpoint (2x SPST N.O. total per gage) |
| Switching Voltage | 20-280 VAC (47-63 Hz) |
| Switching Current | 1.0 A AC max; 0.01 mA AC min |
| Electrical Connections | 18 in (46 cm) cable assembly with 6 conductors; optional extension lengths to 100 ft (30.5 m) |
| Power Requirements | 24 VDC, regulated +/-10% |
| Setpoint Adjustment | Adjustable knobs on gage face (-TAMP option for tamper-proof spanner-key knobs) |
| Mounting Orientation | Diaphragm in vertical position (consult factory for other orientations) |
| Dial Face Diameter | 4 in (101.6 mm) |
| Overall Dimensions (Standard Bezel) | 5 in (127 mm) OD x 3-1/8 in (79.38 mm) deep |
| Overall Dimensions (-SS Stainless Bezel) | 4-3/4 in (120.7 mm) OD x 2-21/32 in (67.5 mm) deep |
| Weight | 1.8 lb (816 g) |
| Panel Mounting Hole | 4-13/16 in (122 mm) standard bezel; 4-9/16 in for -SS stainless bezel |
| Wetted Materials | Consult factory |
| Compliance / Listings | CE |
| Calibration | Factory calibrated; -NIST option for NIST traceable certificate |
| Country of Origin | USA |
What’s In the Box
- Dwyer 3000MRS-60PA Photohelic Differential Pressure Switch/Gage (4 in dial face)
- 18 in (45 cm) cable assembly with multi-pin connector (6 conductors)
- Mounting ring and snap ring (for panel mounting)
- Four 6-32 x 1-1/4 in RH machine screws (panel mounting)
- Three 6-32 x 5/16 in RH machine screws (surface mounting)
- Two 3/16 in tubing to 1/8 in NPT adapters
- Two 1/8 in NPT pipe plugs (for unused side or back ports)
- Installation and operating instructions (also available below as PDF)
Related Products
Same range, but with electromechanical Form C SPDT relays and gold-over-silver contacts - ideal for dry-circuit signal switching.
Documentation
Frequently Asked Questions
The 3000MRS-60PA is a Series 3000MRS Photohelic® Differential Pressure Switch/Gage — a compact, solid-state-controlled combination of a differential pressure gage and a dual-setpoint switch in one 4 in dial-face housing. This model is calibrated for 0-60 Pa. Compared to the standard Dwyer A3000 Photohelic, the 3000MRS is much more compact (3-1/8 in deep vs. 8-1/4 in), much lighter (1.8 lb vs. 4 lb), and runs on 24 VDC instead of 120 VAC. Pressure ports are duplicated on both side and back. Switch is single-pole (SPST N.O.) rather than the A3000's DPDT — sufficient for most alarming applications.
Pick the 3000MRS (solid-state) when the application involves high cycle rates (rapid alarm sequencing, OEM cycling equipment, automated test stands) where electromechanical contact wear would limit service life. Solid-state relays have effectively unlimited switching life with no contact bounce, no arc damage, and no mechanical wear. The trade-off: AC switching only (20-280 VAC, 1.0 A AC max), and outputs are SPST N.O. only (no N.C. contact available). Pick the 3000MR (electromechanical) instead if you're switching dry-circuit signal-level loads (PLC, BMS, DCS inputs - the gold over clad silver contacts excel here), need both N.O. and N.C. contacts per setpoint, or need to switch DC loads.
The 3000MRS requires 24 VDC regulated power, +/-10% tolerance — it is not designed for AC line voltage (do NOT apply 120 VAC to the power input or you will damage the unit). Wiring is via an included 18 in (45 cm) cable assembly with a multi-pin female connector on one end (plugs into the rear of the gage) and bare lead wires on the other end (terminate to your control panel terminal strip). The harness has 6 conductors: Red (24 V+), Black (24 V-), Green (Low Setpoint, first lead), Blue (Low Setpoint, second lead), White (High Setpoint, first lead), Orange (High Setpoint, second lead). Optional cable lengths to 100 ft (30.5 m) available from Dwyer.
Yes, recommended for switching inductive AC loads (solenoid valves, contactor coils, relay coils, etc.). The R/C snubber protects the solid-state relay from inductive kickback voltage spikes that could otherwise exceed the 280 VAC switching limit. Order Dwyer P/N A-600. For pure resistive AC loads, no snubber is required. Note: solid-state relays in this model do not switch DC.
Two mounting methods are supported: (1) Panel mounting - cut a 4-3/4 in (120 mm) diameter hole in the panel, insert the gage from the front, slip on the supplied mounting ring and snap ring from behind, and tighten the four supplied 6-32 x 1-1/4 in screws. (2) Surface mounting - drill three 3/16 in diameter mounting holes (4-1/8 in bolt circle) and one 7/8 in wire-pass hole on the mounting surface, then screw the gage into place with the three supplied 6-32 x 5/16 in screws. If using rear pressure ports, also drill two 1/2 in clearance holes for the tubing. For -SS stainless bezel option: panel hole is 4-9/16 in (matches the Magnehelic® gage cutout for drop-in field upgrade).
The gage has two complete sets of 1/8 in female NPT pressure ports — one set on the side, one set on the back. Use only one set, and plug the unused set with the supplied 1/8 in NPT pipe plugs. Choose whichever orientation suits your tubing routing — the side ports work well for surface-mounted gages, the back ports for through-panel installations where tubing runs straight back out of the panel. Connect the higher-pressure source to the HI port, the lower-pressure source (or atmosphere reference for gauge readings) to the LOW port. Zero the gage before plumbing the pressure source — with both ports open to atmosphere, turn the small slotted screw at center-bottom of the gage face until the needle reads exactly zero.
Yes — that's the purpose of the -SS stainless bezel option. The -SS bezel has the same installation diameter as a standard Magnehelic® gage. Field upgrading from a Magnehelic to this Photohelic switch/gage requires no new hole cutting in the panel: simply unscrew the Magnehelic, swap in this Photohelic with the -SS bezel, secure with the supplied mounting hardware, and wire up the 24 VDC harness. Order code: 3000MRS-60PA-SS. Note: this only applies when ordered with the -SS option; the standard bezel uses a 4-3/4 in / 120 mm panel cut.
Standard rating: 25 psig (1.72 bar) with -20 in Hg (-0.677 bar) negative pressure handling. For higher-pressure systems, two factory-installed options upgrade the rating: -MP option (Medium Pressure): 35 psig (2.41 bar) max, and -HP option (High Pressure): 80 psig (5.52 bar) max. Specify the option suffix at order time. Temperature range is 20-120 deg F (-6.67 to 48.9 deg C); for use below 20 deg F, specify the -LT low-temperature option. For weatherproof outdoor installations, the -WP option adds a weatherproof housing.
