Mercoid 123 Series Specifications-Installation And Operating Instructions

Series 123/125 Boiler Water Level Control
Specifications - Installation and Operating Instructions
By Dwyer
The SERIES 123 & 125 Boiler Water Level Controls are designed for boiler
applications, the 123 is primarily used for low water cut-off or feed-water control. The
125 offers the same long lasting service with a direct action mercury switch movement
that provides a close deadband where needed.
FEATURES/BENEFITS
• Special snap action switch mechanism options eliminates frequent operation due to
surging water level
• Transparent cover provides convenient visible operation of the switch
• Flanged chamber for easy clean out and replacement of float or switch mechanism
without removing the unit from piping
APPLICATIONS
• Boiler Low Water Cut-Off
• Boiler Feed-Water Control
• Condensate Tanks
• Deaerators
MOUNTING
Install control so that lower part of float casting designated as "C-C" (Figure 1) is in line
with lower glass gauge fitting. "C-C" should at no time be installed below crown sheet
of boiler. Use 1" pipe for both steam and water equalizers. Provide value below control
for blowing out sludge periodically as shown in Figure 2.
D
C
MERCOID
A DIVISION OF
DWYER INSTRUMENTS, INC.
P.O. BOX 373 • MICHIGAN CITY, INDIANA 46360, U.S.A.
B B
1-1/8
[28.58]
A A
C
Figure 1
ø5-3/4
[146.05]
5-1/2
[139.70]
7
[177.80]
SPECIFICATIONS
Service: Compatible liquids. Cast iron is not for use with lethal or flammable
substances either liquid or gaseous.
Wetted Materials: Body: Cast iron; Float: 304 SS; Trim and packing gland: Brass;
Packing: Carbon; Body gasket: Carbon.
Temperature Limit: 365°F (185°C).
Pressure Limit: 150 psig (10.34 bar).
Enclosure Rating: General purpose. Optional weatherproof.
Switch Type: SPDT snap switch or mercury switch. Optional DPDT or two stage.
Electrical Rating: Snap switch: 15 A @ 120/240/480 VAC, 0.5 A @ 120 VDC
resistive, 0.25 A @ 240 VDC resistive; Mercury switch: 4 A @ 120 VAC/DC, 2 A @
240 VAC/DC.
Electrical Connections: Screw terminal.
Conduit Connection: 7/8˝ (22.23 mm) hole for 1/2" (12.7 mm) conduit.
Process Connections: 1˝ female NPT.
Mounting Orientation: Vertical.
Deadband: Approximately 1-1/2˝ (38.1 mm).
Specific Gravity: 0.88 min.
Options: Manual reset.
Weight: 20 lb (9.1 kg).
Agency Approvals: CSA, UL. (Snap switch is not rated).
1-13/16
[46.04]
Phone: 219/879-8000
Fax: 219/872-9057
Bulletin IN-47
1 NPT
TYP 2 PLACES
1-1/8
[28.58]
B B
A A
1/2 NPT
PIPE PLUG
3-9/16
TYP 2 PLACES
[90.50]
5-3/8 4-3/4
[136.53] [120.65]
www.dwyer-inst.com
e-mail: info@dwyermail.com
3-9/16
[90.50]
7-1/8
[180.98]
2-7/16
[61.91]