Dwyer Instruments Magnehelic 2000-0-AF User manual

The Magnehelic®gage consists of two pressure-tight compartments separated by
a molded flexible diaphragm.
The interior of the gage case serves as the “high” pressure compartment and a
sealed chamber behind the diaphragm serves as the “low” pressure compartment.
Differences in pressure between the “high” and “low” sides of the diaphragm cause
the diaphragm to assume a balanced position between the two pressures. The
front support plate of the diaphragm is linked to a leaf spring which is anchored at
one end. The spring provides calibrated resistance to the diaphragm motion.
Motion of the spring is transmitted through an exclusive magnetic linkage to the
pointer.
The Magnehelic®gage requires no maintenance. The only field adjustment
required is occasional zero setting of the pointer which is done by opening the
plastic vent valves and turning the adjustment of the gage.
STANDARD ACCESSORIES FURNISHED
Two 1/8˝ NPT plugs for duplicate pressure taps, two 1/8˝ pipe thread to rubber
tubing adapter and three flush mounting adapters with screws. (Mounting and snap
ring retainer substituted for 3 adapters in MP & HP gage accessories.)
The Magnehelic®gage with molded plastic vent valves for easy zeroing. Available
with adjustable signal flag (not shown; option “ASF” at extra cost) for immediate
visual reference to maximum allowable pressure drop; External front screw for zero
adjustment. Red and green scale overlays to highlight safe and dangerous
readings are also available.
Series 2000 Magnehelic®Air Filter Gages
Bulletin A-28
DWYER INSTRUMENTS, INC. Phone: [phone] www.dwyer-inst.com
P.O. BOX 373 • MICHIGAN CITY, INDIANA 46361, U.S.A. Fax: [phone] e-mail: [email protected]
FEATURES
• Easiest reading for personnel accustomed to dial type gages.
• Lowest cost pointer type gage.
• Easy zeroing with molded plastic vent valves.
• Sensitivity to 0.01˝ w.c.
• Withstands vibration.
• Unaffected by over range pressure surges.
SPECIFICATIONS
Service: Air and non-combustible, compatible gases. (Natural Gas option
available.)
Wetted Materials: Consult Factory.
Housing: Die cast aluminum case and bezel, with acrylic cover, Exterior finish is
coated gray to withstand 168 hour salt spray corrosion test.
Accuracy: ±2% of full scale (±3% on - 0 and ±4% on - 00 ranges), throughout
range at 70°F (21.1°C).
Pressure Limits: -20˝ Hg. to 15 psig.† (-0.677 bar to 1.034 bar); MP option; 35
psig (2.41 bar), HP option; 80 psig (5.52 bar).
Overpressure: Relief plug opens at approximately 25 psig (1.72 kPa), standard
gages only.
Temperature Limits: 20 to 140°F.* (-6.67 to 60°C).
Size: 4˝ (101.6 mm) Diameter dial face.
Mounting Orientation: Diaphragm in vertical position. Consult factory for other
position orientations.
Process Connections: 1/8˝ female NPT duplicate high and low pressure taps -
one pair side and one pair back.
Weight: 1 lb 2 oz (510 g), MP & HP 2 lb 2 oz (963 g).
* Low temperature models available as special option.
† For applications with high cycle rate within gage total pressure rating, next higher
rating is recommended. See Medium and High pressure options at lower left.
Model
Number
2000-0-AF
2001-AF
2002-AF
2003-AF
2004-AF
Range
0-.5˝ water
0-1˝ water
0-2˝ water
0-3˝ water
0-4˝ water
Minor
Divisions
0.01˝
0.02˝
0.05˝
0.10˝
0.10˝
OPERATING RANGES AVAILABLE
Specifications - Installation and Operating Instructions
11/16
[17.46]
1/8 LOW
PRESSURE
7/16
[11.11]
1-11/16
[42.86] 1/2
[12.70]
1/8 NPT LOW
PRESSURE
1/8 NPT HIGH
PRESSURE
1/2
[12.70]
1/8 NPT HIGH
PRESSURE
Ø4-1/8 [104.78] BOLT
CIRCLE FOR PANEL MOUNTING
120 APART
1-1/4
[31.75]
Ø4-3/4
[120.65]
1-3/4
[44.45]
Air Filter accessories furnished are mounting
panel with necessary screws, two static
pressure tips with integral compression
fittings, two five foot lengths of 1/4˝ aluminum
tubing and the two molded plastic vent valve
with compression fittings.
Cutaway view of the Magnehelic® gage showing
the actuating diaphragm, the leaf spring with
magnet, the helix which turns the indicating pointer
in response to the position of the magnet without
mechanical linkages.
A-28:bull. A-28 7/16/10 9:31 AM Page 1

DWYER INSTRUMENTS, INC. Phone: [phone] www.dwyer-inst.com
P.O. BOX 373 • MICHIGAN CITY, INDIANA 46361, U.S.A. Fax: [phone] e-mail: [email protected]
INSTALLATION PROCEDURE
1. Screw vent valves into side connections of gage. Be sure back connections of
gage are sealed with plugs provided with the gage. Attach gage to mounting
plate with three No. 6-32 screws provided.
2. Select a convenient location on filter wall and punch or drill four 1/8˝ dia. max.
holes for mounting plate as shown in drawing above. Attach mounting plate
to filter wall with four self-tapping screws provided. If gage is to be flush
mounted in control panel, refer to Bulletin No. A-27.
3. Drill two 7/16˝ holes in the duct, one on each side of the filter and at least 12”
distant*. Secure the static pressure tips as in the drawing above, with the tips
directed into the air flow.
4. Connect 1/4˝ metal tubing from the static pressure tips to the gage. The tip on
the downstream side of the filter is connected to the vent valve in the low
pressure connection of the gage. The tip on the upstream side is connected
to the vent valve in the high pressure connection.
5. Turn both vent valves to “VENT” position and adjust the gage pointer to zero
by means of the external adjustment screw in the face of the gage. After
zeroing, turn vent valves to “LINE” position.
*NOTE On location of static pressure tips: The location of static pressure tips
is of primary importance in securing reliable readings. For maximum accuracy, it is
essential that the influence of the velocity of the air be eliminated to permit sensing
the true static pressure. Note that some installations do not provide a straight duct
approach to the filter bank which may cause air to swirl and eddy.
Tips should be located as recommended by the specifying engineer or by the filter
manufacturer. In the absence of such recommendations, locate the tips at least 12˝
upstream and downstream from the filters in a zone of minimum turbulence.
INSTALLATION CHECK AND TROUBLE SHOOTING
Before putting your air filter gage into service or in the event of initial pressure drop
readings that do not agree with the filter manufacturer’s specified pressure drop,
make the following checks:
1. Check zero adjustment of the gage as described above.
2. Check all tubing connections for tightness from the gage to the static tip or
fitting connection.
3. Check plastic cover of gage to be sure it is securely in place and air tight.
4. Check static pressure tips or fittings to be sure they are not plugged.
5. Check installation of static tips or fittings*. Be sure static pressure tips point
directly into the air stream. A velocity pressure error can be created if the air
blows directly into the opening.
OPERATION
With vent valves in “LINE” position the gage will indicate pressure drop across the
filter. If the reading varies substantially from the filter manufacturer’s rating for a
clean filter, check the system for proper setting of controls, air balancing of system,
leakage in system and whether or not the correct filter has been installed.
When pressure drop across the filter reaches the minimum recommended by the
manufacturer, the filter should be serviced or replaced.
FILTER WALL
AIR FLOW
HIGH PRESSURE
LINE
LOW
PRESSURE LINE
12˝ BETWEEN
STATIC TIPS AND FILTER
Options Not Shown:
- Automatic signal flag integral with plastic gage cover
- Not shown Scale plate overlays in green and red
©Copyright 2010 Dwyer Instruments, Inc. Printed in U.S.A. 7/10 FR# 12-440238-00 Rev. 3
A-28:bull. A-28 7/16/10 9:31 AM Page 2