Dwyer Instruments Mark II 41-2, Mark II 41-600 Pa, Mark II 41-2-AV, Mark II 40-1-AV, Mark II 40-250-AV Installation And Operating Instructions Manual

15/64 [5.95] x 13/32 [10.32] MOUNTING SLOT

10-5/8 [269.88]

5-5/16

[134.95]

MAX

4-5/8

[117.48]

2-31/32
[75.41]

25/32

[19.84]

Ø15/64 [5.95] MOUNTING HOLE

1-1/4

[31.75]

2-1/4 [57.15]

MAX

4 [101.60]

MARK II MODEL 40

Bulletin D-59

Mark II - Model 40 Molded Plastic Manometers

Installation and Operating Instructions

Dwyer Mark II - Model 40 Molded
Plastic Manometers are ideally suited

for air velocity and air filter gage applica­tions at minimal cost. These inclined
manometers provide linear calibration
and excellent resolution throughout their
ranges. They are capable of pressure

line spaced 2-31/32˝ apart. Install the
gage with the self-tapping screws provided,
turning the screws down snug but not tight.
Adjust the position of the gage until the bub­ble is centered in the spirit level. Tighten the
mounting screws, checking to be sure the
instrument remained level, and re-level
as necessary.

measurements above and below
atmospheric, as well as differential pres­sure measurements.

INSTALLATION

Mount the

Stationary Applications:

Mark II manometer on a convenient vertical
surface. The installation should not be
exposed to strong chlorine atmospheres or
solvents such as benzene, acetone, carbon
tetrachloride, etc. The instrument is suitable
for total internal pressures of up to 15 psi
(100 kPa) and ambient temperatures of
150°F (65°C). DO NOT EXCEED THESE
LIMITS. At the mounting location selected,
drill two 9/64˝ diameter holes on a vertical

DWYER INSTRUMENTS, INC.

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

SPECIFICA T IONS
Accuracy

: ±3% of full scale.

Maximum Internal Working Pressure:

15 psi (100 kPa).
Maximum Working Temperature: 150°F
(65°C).

Scale Length: Approx. 8-1/4˝ (21 cm).
Weight: 10 oz (283.49 g).
Accessories: 3/4 oz. gage oil, mounting

screws, 1/8˝ NPT tubing adapters, wash­ers, nuts, red and green pointer flags, (2)

4-1/2 ft.

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

lengths 3/16˝ I. D. vinyl tubing.

Portable Applications: For portable

use, a molded plastic swing-away foot and
leveling screw are provided. Referring to the
picture on the first page of this bulletin,
secure the swing-away foot to the bottom of
the gage, using the plastic screw in the
tapped hole on the right-hand side. Install
the plastic leveling screw in the tapped hole
on the bottom left side of the manometer. In
use, the swing-away foot is positioned per­pendicular to the gage. With the manometer
in operating position, the leveling screw is
adjusted until the bubble is centered in the
spirit level. For storage, the swing-away foot
can be rotated to a position in line with the
gage body.

FILLING

T urn the zero adjust knob fully counter clock­wise until it stops; then turn it clockwise
approximately four full turns so as to center
the adjustment to allow room for adjusting
either side of zero. Unscrew the entire low
pressure (right) shut-off connection fitting. A
3/4˝ wrench is required. Also, remove the
cork, disc, and “O” ring. Vent the left con­nector by turning the elbow 1 - 2 turns
counterclockwise. Slowly fill gage with fluid
provided until fluid rises in the indicating
tube to the vicinity of zero on the scale.
Nearly all the oil provided will be required to
fill the gage. Replace the cork, disc, “O” ring
and the low-pressure shut-off
connection fitting.

OPERATION

The Model 40 manometer is provided with
convenient shut-off tubing connections to
prevent loss of oil when transporting the
gage. To use the gage, turn each barbed
tubing connection counterclockwise 1-2
turns from the closed (fully clockwise) posi­tion. Rotate the zero adjustment for an exact
zero reading and the gage is ready for use.
In stationary installations, these steps need
only be performed upon initial installation. In
portable use, each time the gage is used the
connections must be opened, the gage lev­eled and zeroed; prior to storage, the gage
connections must be closed.

Pressure Connection: Two 4-1/2˝

lengths of plastic tubing are included with
the gage along with two adapters for con­nection of the tubing to 1/8˝ NPT fittings or
sheet metal ducts. The tubing from the high
pressure pickup should be connected to the
high pressure (left) barbed connection at the
top of the gage. The tubing from the low
pressure pickup should be connected to the
low pressure (right) barbed fitting. Stick-on
red and green arrows are provided to indi­cate the appropriate range of readings for
the particular application. The 1/8˝ NPT
tubing adapters can be used as static pres­sure sensors in sheet metal ducts by drilling
a 7/16˝ diameter hole in the duct and
mounting the adapter in the hole, placing
one of the washers on each side of the duct
wall and securing the 1/8˝ NPT nut.

CAUTION

USE .826 SPECIFIC GRAVITY RED
GAGE OIL FOR MODEL #’S 40-1, 40-1­AV, 40-250 Pa, 40-250 Pa-AV, and 40­25 mm. Use 1.910 SPECIFIC GRAVITY
BLUE GAGE OIL FOR MODEL #’S 41­2, 41-2-AV, 41-600 PA, 41-60 mm.

TYPICAL APPLICATIONS
Draft Gage: Run iron pipe, 1/8˝ or larg-

er in size, from the source of the draft to a
point within 4-1/2˝ of the manometer.
Provide a means for periodic clean-out to
remove any soot accumulation. Using one
of the lengths of tubing provided, make the
connection from the pipe to the low pres­sure (right) fitting on the gage.

Static Pressure Indicator: Using the

1/8˝ NPT tubing adapters provided, make a
static pressure connection to the duct at the
desired location. Using either the tubing pro­vided or a longer length if necessary , connect
the pressure sensor to either the high (left) or
low (right) pressure connection of the gage,
depending on whether the static pressure is
positive or negative compared to atmos­phere. Where air velocities in the duct are
1000 ft. per minute or higher, static pressure
error may be induced unless a static pres­sure tip is used.

Air Filter Gage: Mount the gage within 4-

1/2˝ of the filter bank and install a 1/8˝ NPT
tubing adapter in the duct on each side of
the filter element. Run the tube from the fit­ting on the discharge side of the filter to the
low pressure (right) gage connection and the
tube from the upstream side of the filter to
the high pressure (left) connection. Remove
the paper backing from the green and red
arrows and install the arrows on the face of
the manometer adjacent to the indicating
tube to indicate clean and dirty filter readings.

The velocity indicated is for dry air at 70°F
(21.1°C), 29.9˝ barometric pressure, and a
resulting density of .075 pounds per cubic
foot. For variations from these standard con­ditions, corrections may be based upon the
following
formula:

Air Velocity (FPM) = 1096.5 √

Pv

D

Where Pv = velocity pressure in in./H2O

D = air density in lbs. per ft
D = 1.325 x Pb

T

3

Where Pb = barometric pressure in

inches of mercury

T = absolute temperature

(indicated °F + 460)

To determine the volume of air flow in the
duct in cubic feet per minute, multiply air
velocity in FPM times the cross-sectional
area of the duct in square feet.

Air Velocity Indicator: A pitot tube is

required for air velocity readings and care
must be taken in installations to insure accu­racy. Select a location for the pitot tube with
smooth straight sections of duct at least 8­1/2 diameters upstream and 1-1/2 or more
diameters downstream. Install the pitot tube
so it is centered in the duct with the tip
directed into the air stream. The right angle
pitot tube connection is connected to the low
pressure (right) gage connection. The
straight pitot tube connection is connected
to the high pressure (left) gage connection.
Velocity reading now indicated on the gage is
the center or maximum air velocity in the
duct. For average velocity across the full
area of the duct, multiply by a factor of .9.

OPERATING RANGES

Model

40-1

40-1-AV*

41-2

41-2-AV*

40-250 Pa

40-250-AV*

Range

.10-0-1.00˝ w.c.

0-1.10˝ w.c.

0-4200 fpm

.20-0-2.400˝ w.c.

0-2.50˝ w.c.

0-6300 fpm

10-250 Pa

0-260 Pa

0-21 mps

Minor
Grads

.01˝ w.c.

.01˝ w.c.

varies

.02˝ w.c.

.02˝ w.c.

varies

2Pa

2Pa
varies

Indicating

Fluid

.826 sp. gr.

(red oil)

.826 sp. gr.

(red oil)

1.910 sp. gr.
(blue oil)

1.910 sp. gr.
(blue oil)

.826 sp. gr.

(red oil)

.826 sp. gr.

(red oil)

41-600 Pa

20-0-600 Pa

5Pa

1.910 sp. gr.
(blue oil)

40-25 mm

0-26 mm w.c.

2 mm w.c.

.826 sp. gr.

(red oil)

41-60 mm

0-60 mm w.c.

5 mm w.c.

1.910 sp. gr.
(blue oil)

* Pitot tube required at additional cost. See Bulletin H-100.

©Copyright 2009 Dwyer Instruments, Inc Printed in U.S.A. 7/09 FR# 67-440433-00 Rev. 3

DWYER INSTRUMENTS, INC.

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

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