Introduction
Series AP Diaphragm Operated Pressure Switches are reliable, convenient, compact, low-cost switches for instrument air or other low-pressure applications. Visible set point and external adjustment add convenience. Used on air, non-corrosive gas or liquid service compatible with wetted parts. These switches are available with optional weather-proof and explosion-proof housings.
Physical Description and Dimensions
The diagram illustrates the physical features and dimensions of the Mercoid Series AP pressure switch. Key features include:
- A 7/8" (22.23 mm) conduit hole and a 7/8" (22.23 mm) knock-out hole.
- A 1/4" NPT process connection.
- Mounting holes are indicated.
- Overall dimensions are provided in inches with millimeter equivalents in brackets, such as 15/16" [23.81], 1-7/16" [36.51], 2-13/32" [61.12], 2-7/8" [73.03], 4-1/8" [104.78], and 3-1/8" [79.38].
- An adjustment screw with sealing wire is visible.
Specifications
| SPECIFICATIONS | |
|---|---|
| Wetted Materials | Nylon reinforced Buna-N and steel. PTFE and 316 SS optional. |
| Temperature Limits | -30 to 150°F (-35 to 66°C). |
| Pressure Limit | See model chart. |
| Enclosure Rating | General purpose. Weatherproof and explosion-proof optional. |
| Switch Type | SPDT mercury switch or SPDT snap switch. Other switch types available. |
| Electrical Rating (Mercury Switch) | 4A @ 120 VAC/DC, 2A @ 240 VAC/DC. |
| Electrical Rating (Snap Switch) | 15A @ 120 VAC, 8A @ 240VAC, 0.5A @ 120 VDC, 0.25A @ 240 VDC. |
| Electrical Connections | Screw terminal. |
| Conduit Connection | 7/8" (22.23 mm) hole for 1/2" (12.7 mm) conduit hub. |
| Process Connection | 1/4" female NPT. |
| Mounting Orientation | Vertical for mercury switch models, any position for snap switch models. |
| Set Point Adjustment | External screw. |
| Weight (General purpose) | 2 lb (0.9 kg). |
| Deadband | See model chart. |
| Agency Approvals | CE, UL, CSA. For FM consult factory. (Mercury switch units are not CE approved.) |
Operating Ranges - Type AP & AP-41 (Mercury Switch)
| Range Number | Suffix Number | Switch Type | Low Pressure | High Pressure |
|---|---|---|---|---|
| 33 | -2 | SPST Opens | 8 in w.c. (205) | 10" w.c. (250) |
| 33 | -3 | SPST Closes | 8 in w.c. (205) | 10" w.c. (250) |
| 33 | -88 | SPST Closes | 3 in w.c. (80) | 3 in w.c. (80) |
| 33 | -89 | SPST Opens | 4 in w.c. (102) | 4 in w.c. (102) |
| 33 | -153 | SPST | 5 in w.c. (127) | 6 in w.c. (152) |
| 36 | -2 | SPST Opens | 1.0 psig [0.07] | 2.0 psig [0.14] |
| 36 | -3 | SPST Closes | 1.0 psig [0.07] | 2.0 psig [0.14] |
| 36 | -26 | SPST Closes | 1.5 psig [0.10] | 2.5 psig [0.17] |
| 36 | -36 | SPST Opens | 1.5 psig [0.10] | 2.5 psig [0.17] |
| 36 | -88 | SPST Closes | 4 in w.c. (102) | 8 in w.c. (205) |
| 36 | -89 | SPST Opens | 6 in w.c. (152) | 12" w.c. (305) |
| 36 | -153 | SPST | 0.3 psig [0.02] | 0.5 psig [0.03] |
| 37 | -2 | SPST Opens | 2.0 psig [0.14] | 3.0 psig [0.21] |
| 37 | -3 | SPST Closes | 2.0 psig [0.14] | 3.0 psig [0.21] |
| 37 | -26 | SPST Closes | 2.5 psig [0.17] | 3.5 psig [0.24] |
| 37 | -36 | SPST Opens | 2.5 psig [0.17] | 3.5 psig [0.24] |
| 37 | -88 | SPST Closes | 6 in w.c. (152) | 12 in w.c. (305) |
| 37 | -89 | SPST Opens | 8 in w.c. (205) | 16 in w.c. (406) |
| 37 | -153 | SPST | 0.8 psig [0.06] | 1.5 psig [0.11] |
| 39 | -2 | SPST Opens | 6 psig [0.41] | 16 psig [1.10] |
| 39 | -3 | SPST Closes | 8 psig [0.55] | 17 psig [1.17] |
| 39 | -26 | SPST Closes | 8 psig [0.55] | 20 psig [1.38] |
| 39 | -36 | SPST Opens | 8 psig [0.55] | 20 psig [1.38] |
| 39 | -88 | SPST Closes | 1.5 psig [0.10] | 3.0 psig [0.21] |
| 39 | -89 | SPST Opens | 1.5 psig [0.10] | 3.0 psig [0.21] |
| 39 | -153 | SPST | 4 psig [0.28] | 10 psig [0.69] |
Operating Ranges - Type AP (Snap Switch)
| Range Number | Adjustable Pressure Range | Max. Approx. Operating Press. | Single SPDT | Approx. Switch Deadband | (2) SPDT Snap Switches | |||
|---|---|---|---|---|---|---|---|---|
| psig | Low | High | Low | High | Low | High | ||
| 33 | 10" vac-50 in w.c. (250 vac-1250) | 15 [1.0] | 8 in w.c. (205) | 10 in w.c. (250) | 4.5 in w.c. (127) | 5 in w.c. (127) | 4.5 in w.c. (127) | 5 in w.c. (127) |
| 36 | 1-20 psig [0.07-1.4] | 60 [4.1] | 0.5 psig [0.04] | 1.5 psig [0.11] | 0.75 psig [0.05] | 1.5 psig [0.11] | 0.75 psig [0.05] | 1.5 psig [0.11] |
| 37 | 1-30 psig [0.07-2.1] | 60 [4.1] | 0.75 psig [0.05] | 1.5 psig [0.11] | 0.75 psig [0.05] | 1.5 psig [0.11] | 0.75 psig [0.05] | 1.5 psig [0.11] |
| 39 | 10-125 psig [0.7-8.6] | 160 [11] | 3 psig [0.2] | 7 psig [.49] | 1.25 psig [0.09] | 4 psig [0.3] | 1.25 psig [0.09] | 4 psig [0.3] |
Model Chart - Series AP
| Example | Construction | Reset Options | Housing Options | Circuit (Switching) Options | Wetted Materials | Adjustable Pressure Ranges & Maximum Operating Pressures | Agency Approvals |
|---|---|---|---|---|---|---|---|
| AP | AP | General Purpose enclosure, NEMA-1. | Mercury switch type. Plated steel pressure port, Buna-N diaphragm. | Adjustable range 10" wc VAC-50" wc (250 mm VAC to 1250 mm wc), maximum pressure 15 psig. | UL CSA | ||
| AS | AS | Low pressure steam switch, NEMA-1, range 34 only. Circuits, 2, 3, 26, 36, 153 only. PTFE covered diaphragm, plated steel pressure port. | Adjustable range 1-15 psig (0.07 to bar), AS only, maximum pressure 30 psig (2.1 bar), maximum temperature 275°F (135°C) psig. | UL CSA | |||
| F | F | Factory Mutual approved, NEMA-1, circuit 153 only. Range 37 only. APF-153-37 or APF-7021-153-37 only. | Adjustable range 1-30 psig (0.07-2.1 bar), maximum pressure 60 psig (4.1 bar). | UL FM CSA | |||
| R | R | Manual reset - operates on decrease automatically. NEMA-1 only. Not available with circuit 88, 89 or snap switch type. | UL CSA | ||||
| U | U | Manual reset - operates on increase automatically. NEMA-1 only. Not available with circuit 88, 89 or snap switch type. | UL CSA | ||||
| S | S | Less enclosure | UL CSA | ||||
| WT | WT | Weather-proof enclosure, NEMA-4. | UL CSA | ||||
| W | W | Weather-proof enclosure with condensate drain, NEMA-2, 3R. | UL CSA | ||||
| H | H | Explosion-proof enclosure, NEMA-7, 9, Class I Group, C & D; Class II Group E, F & G. | UL CSA | ||||
| 2 | SPST mercury switch, Electrical Code P* - opens on pressure increase. | Mercury switch type. Plated steel pressure port, Buna-N diaphragm. | Adjustable range 1-20 psig (0.07-1.4 bar), maximum pressure 60 psig (4.1 bar) | UL CSA | |||
| 3 | SPST mercury switch, Electrical Code P*- closes on pressure increase. | Mercury switch type. 316 stainless steel pressure port, PTFE diaphragm. | Adjustable range 1-30 psig (0.07-2.1 bar), maximum pressure 60 psig (4.1 bar). | UL CSA | |||
| 26 | SPST mercury switch, Electircal Code R* - closes on pressure increase. Not available with range 33. | Snap switch type. Plated steel pressure port, Buna-N diaphragm. | Adjustable range 10-125 psig (0.7-8.6 bar), maximum pressure 160 psig (11 bar). | UL CSA | |||
| 36 | SPST mercury switch, Electrical Code R* - opens on pressure increase. Not available with range 33. | Snap switch type. Plated steel pressure port, Buna-N diaphragm. | UL CSA | ||||
| 88 | SPST magnetic mercury switch, Electrical Code T* - closes on pressure increase. | Snap switch type, 316 stainless steel pressure port, PTFE diaphragm. | UL CSA | ||||
| 89 | SPST magnetic mercury switch, Electrical Code T* - opens on pressure increase. | Snap switch type, 316 stainless steel pressure port, PTFE diaphragm. | UL CSA | ||||
| 153 | SPDT mercury switch, Electrical Code S*. | UL CSA | |||||
| () | Other circuits available, consult factory. | UL CSA | |||||
| 70_ - 153 | SPDT snap acting switch, rated 15A at 120 VAC, 8A at 240 VAC, 0.5A at 120 VDC, 0.25A at 240 VDC, 3/4 hp at 120 VAC, 1 hp at 240 VAC. | UL CSA | |||||
| 70__ 804 | DPDT: 2 each SPDT snap acting switches, rated 5A at 120/240 VAC, 5A at 30 VDC resistive SPDT snap acting switch, rated 15A at 120 VAC, 8A at 240 VAC, 4A at 480 VAC, 6A at 24 VDC resistive, 0.5A at 120 VDC, 0.25A at 240 VAC, 3/4 hp at 120 VAC, 1.5 hp at 240 VAC. | UL CSA | |||||
| 80_ - 153 | UL CSA | ||||||
| 41 | Mercury switch type. Plated steel pressure port, Buna-N diaphragm. | UL CSA | |||||
| 7021 | Mercury switch type. 316 stainless steel pressure port, PTFE diaphragm. | UL CSA | |||||
| 8021 | Snap switch type. Plated steel pressure port, Buna-N diaphragm. | UL CSA | |||||
| 7041 | Snap switch type. Plated steel pressure port, Buna-N diaphragm. | UL CSA | |||||
| 8041 | Snap switch type, 316 stainless steel pressure port, PTFE diaphragm. | UL CSA |
Electrical Rating - Mercury Switch
| Code | Circuit Suffix No. | AC Capacity | DC Capacity | Horsepower | ||||
|---|---|---|---|---|---|---|---|---|
| 120V | 240V | 440V | 120V | 240V | AC | DC | ||
| P | -2, -3 | 10A | 5A | 3A | 10A | 5A | 3/4 | 1/3 |
| R | -26, -36 | 17A AT 120/240/277 VAC, Resistive balance same as above. | ||||||
| S | -153 | 4A | 2A | NA | 4A | 2A | 1/8 | NA |
| T | -88, -89 | 0.5A | 0.25A | NA | 0.25A | 0.125A | ||
Operation and Application
Type AP and AP-41 with Suffix No's. -153, -2, -3, -26, 36, -88, -89 (Mercury Switch)
Operation: A variation in control pressure causes the diaphragm to actuate the hermetically sealed mercury switch to open or close the electrical contact.
Application: Type AP with suffix numbers -153, -2, -3, -26, -36, -88, -89 are for use with mediums not injurious to steel, silver solder or Fairprene diaphragm. Type AP-41 with suffix numbers -153, -2, -3, -26, -36, -88, -89 are for use with mediums not injurious to 316 SS and PTFE.
Type AP and AP-41 with Suffix No's. 153, -2, -3, -26, 36, -88, -89 (Snap Switch)
Operation: A variation in control pressure causes the diaphragm to actuate the snap action switch.
Applications: Type AP, APH, APW, APWT with suffix numbers 7021-153 or 8021-153 are for use with mediums not injurious to steel, silver solder, Nylon/Buna-N diaphragm. Type AP, APH, APW, APWT with suffix numbers 7041-153 or 8041-153 are for use with mediums not injurious to 316 SS and PTFE covered diaphragm.
Mounting
Mercury Switch Models
Install control firmly in a LEVEL POSITION on a panel or smooth wall surface by means of two mounting ears. Where pipe mounting is desired, control may be connected by means of the 1/4" I.P.S. connection. Do not mount control by twisting the case; use a wrench on the square part of the 4" bottom pipe connection. To level, sight across the two cover screws or check the lower end of the glass opening in the cover to see that instrument is lined up horizontally.
Snap Switch Models
Mount in any position. Type AP (general purpose) can be installed on a panel or smooth surface using the two mounting ears or the 4" NPT bottom connection. Do not mount by twisting the case; use a wrench on the square part of the 4" bottom pipe connection. Type APW-NEMA 3 (weather-resistant): 4" male NPT bottom connection. Type APWT-NEMA 4 (water-tight): 4" male NPT bottom connection. Type APH (explosion-proof): 4" male NPT bottom connection. Or use mounting bracket No. PP-135-95
Wiring
Wire in accordance with local electrical codes or equipment manufacturers' instructions. See nameplate attached to inside of control case for terminal markings and electrical rating. Do not overload. Do not oil any parts. Do not tamper with switch wires. Position of these wires is essential for proper operation. Tampering with these wires will void warranty.
For snap switch models, wire in accordance with the national Electrical code and local regulations. Observe wiring diagram inside enclosure and details below for type No. and electrical rating. Where control is connected directly into the load circuit, it must be wired into hot side of line. Do not overload. Do not oil any parts.
Wiring Diagram
All Types Single-Pole, Double-Throw (-153) or Double-Pole, Double Throw (-804) Operation
- -153 - SP-DT: Common, On Hi, On Lo
- -804 - DP-DT: Common, On Hi, On Lo (for each pole)
Adjustments
Turn adjustment screw "A" until pointer on dial indicates desired operations pressure.
Electrical Rating - Snap Switch Models
| SERIES | SWITCH TYPE | RATING |
|---|---|---|
| 7021-153 & 7041-153 | SPDT | 15A max. 120V AC; 8A MAX. 240V AC |
| 8021-153 & 8041-153 | SPDT | 15A max. 120V AC; 8A 240V AC; 0.5A max. 120V DC; 0.25A 240V DC 4A 480V AC 3/4 Hp. 120V AC. 1 Hp. 240V AC |
| 7021-804 & 7041-804 | (2 SPDT) | 5A 120/240 AC -- 30V DC resistive |
Contact Information
For more information or to find quality products online, please visit:
Mercoid Division
Dwyer Instruments, Inc.
Phone: 219/879-8000 | Fax: 219/872-9057
Email: info@dwyermail.com | sales@GlobalTestSupply.com
Copyright © 2014 Dwyer Instruments, Inc. Printed in U.S.A. 2/14
