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Mercoid Series “D” Pressure Controls

feature hermetically

sealed mercury switches, Bourdon tube power elements, visible
setpoint, adjustable deadband or fixed deadband and pressure
ranges from 0-30” Hg. Vac to 800-8000 psig (345 bar).

FEATURES 

• Visible calibrated dial
• On/off indication
• Adjustable, fixed deadband, or manual reset
• External switch setpoint adjustments
• Minimum deadband is obtainable at any point in the range
• Pressure Ranges of full vacuum to 8000 psig.
• UL listed, CSA approved. Many models FM approved.
• General purpose, weatherproof or explosion-proof

enclosures

• Single or two stage operation

SPECIFICATIONS
Wetted Materials:

Brass, 403 SS, or 316 SS.

Temperature Limit:

180°F (82°C).

Pressure Limit: 

Maximum pressure of the operating range.

Enclosure Rating: 

General purpose, weatherproof or explosion-

proof.

Repeatability:

±1% of full operating range.

Switch Type: 

See circuit chart.

Electrical Rating: 

See electrical ratings chart.

Electrical Connections: 

Screw terminal.

Conduit Connection: 

General purpose: 1/2˝ hole for conduit

hub. Weatherproof: 1/2˝ conduit hub. Explosion-proof: 3/4˝ female
NPT.

Process Connection: 

General purpose and weatherproof: 1/4˝

male NPT, 1/2˝ male NPT on ranges 15S and 16S. Explosion-
proof: 1/2˝ male NPT and 1/4˝ female NPT.

Mounting Orientation:

Vertical.

Set Point Adjustment:

Thumbscrew.

Weight: 

General Purpose: 4 lb (1.8 kg), weatherproof: 6 lb

(2.7kg), explosion-proof: 8 lb (3.5 kg).

Deadband:

See Ranges and Differentials Chart.

INSTALLATION

Location and Mounting

Select a location that is recommended by equipment manufacter
and reasonably free from vibration caused by reciprocating or
rotating machinery.  Where excessive vibration occurs, use a
remote connection and mount by means of a mounting bracket or
separable flange (available on order).  When in doubt about exces-
sive vibration, use a remote connection. Where pulsations, pres-
sure surges, or water hammer are present, protect the control with
a surge tank or scrubber. 

Mount all controls vertically and

level.

General Purpose Controls:

Install controls prefixed by the let-

ters DA, DAF, DRF, DL, DS, DSF, firmly in a level position.  Do not
mount the control by twisting the case; use a wrench on the
square part of the 1/4

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 the control is lined up horizontal-
ly.  On general purpose controls provided with a flange, mount by
means of the three holes in the flange.  

Series “D” Pressure Controls with Mercury Switches

Specifications - Installation and Operating Instructions

Bulletin IN-0118

1/4 N.P.T.

6-1/64

[152.8]

DIA.

7/8 [22.23]

ADJUSTMENT SCREWS

2-1/4

[57.15]

1-5/8

[41.28]

1/2 [12.7]

CONDUIT HOLE

5/8 [15.88]

MERCOID
CONTROL

MERCOID DIVISION

DWYER INSTRUMENTS, INC.
P.O. BOX 258 • MICHIGAN CITY, INDIANA 46361 U.S.A.

Phone: 219/879-8000

www.dwyer-inst.com

Fax: 219/872-9057

e-mail: [email protected]

Remote Connection

No. 49-62 (300 psi)

No. 49-62HP (to 2500 psi)

Mounting Bracket

No. 33-25     

Pigtail Siphon

No. 42-52 (300 psi)

No. 42-58 (2,000 psi)

ACCESSORIES

6-

1/2

 DIA.

13/64

DIA.

BACK

CONNECTION

BOTTOM CONNECTION

DA-24
DA-34
DA-44

DA-23
DA-33
DA-43

HOLES FOR

FLANGE SCREWS

1/2

 CONDUIT

CONNECTION

5-3/4

 DIA.

1/4

 NPT

1-

1/2

1/4

 NPT

1-1/8

DA-21
DA-31
DA-41

DA-22
DA-32
DA-42

General Purpose with

Flange for Surface Mounting

General Purpose

IN-0118  10/24/06  1:35 PM  Page 1

Summary of Contents for D Series

Page 1: ... from vibration caused by reciprocating or rotating machinery Where excessive vibration occurs use a remote connection and mount by means of a mounting bracket or separable flange available on order When in doubt about exces sive vibration use a remote connection Where pulsations pres sure surges or water hammer are present protect the control with a surge tank or scrubber Mount all controls verti...

Page 2: ...tomatically on a decrease of pressure with provision for man ual reset when pressure is below set point Prefixed by DL DLW DLE DLH A single adjustment sets the low pressure operating point of the control at any value on the scale range The control will operate automati cally at the set point only on a drop in pressure The lock type feature per mits the circuit to be reset and locked in position wh...

Page 3: ...C on Page 4 in Electrical Rating Chart Spec No Pressure 4122 4129 4132 4123 Switch Mk A B A B A B A B Low Pressure Hi Vac ON ON OFF OFF ON OFF OFF ON Intermediate Pressure OFF ON ON OFF OFF OFF ON ON High Pressure Lo Vac OFF OFF ON ON OFF ON ON OFF Two Stage Series D 400 Switch Operating Specifications When ordering select operation desired add suffix number to type number of control Example Type ...

Page 4: ...ircuit 2 Circuit SP DT SP DT SP ST SP DT ST ST DP DT Code A A B A A B A A A B B B B A B A B A B B B Circuit Response to Pressure Increase Opens Closes Closes Closes Opens Opens Closes Closes Opens One Closes as Other Opens One Closes as Other Opens Close Opens Closes Open One Closes as Other Opens One Opens as Other Closes Closes One Closes as Other Opens Opens Two Close Two Open 4P ST Close 2 9 6...

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