Series Mark II Molded Plastic Manometers

3% Accuracy for Stationary and Portable Applications

Dwyer® Mark II series molded manometers are of the inclined and inclined-vertical types. The curved inclined-vertical tube of the Model 25 gage provides higher ranges with more easily read increments at low readings. The Model 25 is excellent for general purpose work. The Model 40 inclined gage provides linear calibration and excellent resolution throughout its range. The Model 40 is ideally suited for air velocity and air filter gage applications. Both gage types are capable of pressure measurements above and below atmospheric as well as differential pressure measurements.

Click here, if you require a Material Safety Data Sheet for the Blue Gage Fluid or the Red Gage Fluid.

Models & Ordering

Filter By

Model Number Description Usually Ships Price Order
MARK II 25 Molded plastic manometer, range 0-3" w.c., red oil, .826 sp. gr. Same Day $35.25 Order
MARK II 26 Molded plastic manometer, range 0-7" w.c., blue oil, 1.91 sp. gr. Same Day $185.00 Order
MARK II 27 Molded plastic manometer, range 0-7000 fpm, red oil, .826 sp. gr., requires Pitot tube sold separately. Same Day $51.50 Order
MARK II 28 Molded plastic manometer, range 0-10,500 fpm, blue oil, 1.91 sp. gr., requires Pitot tube sold separately. 1-2 Weeks $190.00 Order
MARK II M-700PA Molded plastic manometer, range 10-0-700 Pa, red oil, .826 sp. gr. Same Day $35.25 Order
MARK II MM-180 Molded plastic manometer, range 0-180 mm w.c., blue oil, 1.91 sp. gr. Same Day $185.00 Order
MARK II MM-80 Molded plastic manometer, range 0-80 mm w.c., red oil, .826 sp. gr. Same Day $39.75 Order


±3% FS.
Temperature Limits:
Inclined/Vertical Models: 140°F (60°C); Inclined Models: 150°F (65°C).
Pressure Limits:
Inclined/Vertical Models: 10 psi (70 kPa); Inclined Models: 15 psi (100 kPa).
Scale Length:
Inclined Models: Approx. 8-1/4" (21 cm).
Inclined/Vertical Models: 1.04 lb (472 g); Inclined Models: 1.23 lb (558 g).


  • Construction - Mark II Manometers are economically priced, compact and available in both stationary and portable configurations. Portable stand is standard on Model 40, available as optional A-612 stand for Model 25. Construction is simple with virtually indestructible molded white styrene-acrylonitrile housing, indicating tube and fluid wells, molded ABS knobs and zero adjust plunger, shock mounted glass level vial and leak proof "O" ring seals. Moderate overpressures are accommodated by an overflow tank incorporated in the Model 25. Greater protection is provided by float operated overflow traps in the Model 40. Scales are lithograph printed on aluminum and epoxy coated.
  • Installation - Mark II Manometers can be mounted on any vertical surface with the two mounting screws provided. A built-in spirit level simplifies leveling before mounting screws are tightened. Simply fill the reservoir, adjust fluid level to zero, connect the tubing, and the gage is ready for operation.
  • Accessories - Included with each Mark II manometer are two tubing connectors for 1/8" pipe or sheet metal ducts, two mounting screws, 1 ounce bottle of indicating fluid, red and green pointer flags and complete instructions.
    The Model 25 also includes 8' of flexible double column plastic tubing. Portable operation of the Model 25 is made possible by the use of the optional A-612 portable stand. A short piece of tubing can be slipped over the Model 25 pressure connections to contain the gage fluid in transit.
    The Model 40 contains two 4-1/2' lengths of clear plastic tubing, a plastic swing-out stand and leveling screw for portable operation. It also features convenient rapid shutoff pressure connections and integral overpressure safety traps.


  • OEM Specials - All Dwyer® Mark II Molded Plastic Manometers can be supplied in OEM quantities with your name and special graphics and scale.


Model Number Description Usually Ships Price Code Order
420706-00 Red pointer indicator. 1-2 Weeks $1.20 N Order
420706-01 Green pointer indicator. 1-2 Weeks $1.20 N Order
A-101 1 oz dispenser bottle of red gage fluid, .826 sp. gr. Same Day $6.80 Order
A-102 4 oz bottle of red gage fluid, .826 sp. gr. Same Day $13.00 Order
A-103 1 pt bottle of red gage fluid, .826 sp. gr. Same Day $30.25 Order
A-104 1 qt bottle of red gage fluid, .826 sp. gr. Same Day $54.50 Order
A-110 1 oz dispenser bottle of blue gage fluid, 1.910 sp. gr. Same Day $124.00 Order
A-111 1 pt bottle of blue gage fluid, 1.910 sp. gr. Same Day $1,645.00 Order
A-220 Clear flexible vinyl tubing is easily inspected, and is therefore best for test applications where a possibility of fluid entering the tubing exists. 3/16" ID x 5/16" OD, lengths to 500'; 45 psi maximum pressure @ 73°F. Same Day $0.25 N Order
A-225 Flexible double column plastic tubing, lt. grey, with red color code stripe, 1/8" ID, lengths to 750 ft, per ft. Same Day $2.99 N Order
A-315 Gage connector, shutoff type, for 3/16" rubber tubing. Same Day $13.50 Order
A-480 Plastic static pressure tip. Same Day $0.80 Order
A-489 4" 303 SS straight static pressure tip with flange. Same Day $6.67 Order
A-606 Air filter kit for Series Mark II. Same Day $33.50 Order
A-612 Portable stand. Same Day $38.25 Order

Product Literature


Catalog Pages




We have a Dwyer gauge Mark II 25 on a waste oil furnace. Can you tell us how much heat it will withstand if we should get it too close to the heat source or how hot the gauge could get before readings would be incorrect.
The maximum temperature the Mark II 25 can be exposed to is 140 degrees F since it has many plastic components that cannot withstand direct heat.
Could you confirm the instructions on setting the zero setting on Dwyer Model Mark II 25. I have two different instructions and want to know which one is correct.
Here is a link to the instruction manual for your model:
The correct steps for zeroing are: Turn the zero set knob counterclockwise until it stops, then turn clockwise 3 full turns. This puts zero in approximately the middle of the travel adjustment in either direction. Remove the fill plug and fill with gage fluid until fluid reaches zero on scale. Minor adjustments can be made to adjust zero by adjusting zero knob. Replace fill plug. If gage is overfilled, remove excess by inserting pipe cleaner through the fill port to blot up excess fluid.

Photo Downloads

You must be logged in to view this content.
Click here to login to your account.