Mercoid 123 Series Installation and operating instructions

Series 123/125 Boiler Water Level Control
Specications - Installation and Operating Instructions
Bulletin IN-47
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oat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oatcastingdesignatedas“C-C”(Figure1)isinline
withlowerglassgaugetting.“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.
SPECIFICATIONS
Service: Compatibleliquids.Castironisnotforusewithlethalorammable
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).
Specic Gravity: 0.88min.
Options: Manualreset.
Weight: 20lb(9.1kg).
Agency Approvals: CSA,UL.(Snapswitchisnotrated).
BB
AA
1/2 NPT
PIPE PLUG
TYP 2 PLACES
7
[177.80]
5-1/2
[139.70]
ø5-3/4
[146.05]
5-3/8
[136.53]
4-3/4
[120.65]
3-9/16
[90.50]
2-7/16
[61.91]
7-1/8
[180.98]
3-9/16
[90.50]
1-1/8
[28.58]
1 NPT
TYP 2 PLACES
BB
AA
C C
D
1-1/8
[28.58]
1-13/16
[46.04]
Figure 1
MERCOID
P.O. BOX 373 • MICHIGAN CITY, INDIANA 46360, U.S.A.
Phone: [phone]
Fax: [phone]
www.dwyer-inst.com
e-mail: [email protected]
A DIVISION OF
DWYER INSTRUMENTS, INC.
By Dwyer

©Copyright 2016 Dwyer Instruments, Inc. PrintedinU.S.A.5/16 FR# 442047-00 Rev. 1
MERCOID
P.O. BOX 373 • MICHIGAN CITY, INDIANA 46360, U.S.A.
Phone: [phone]
Fax: [phone]
www.dwyer-inst.com
e-mail: [email protected]
A DIVISION OF
DWYER INSTRUMENTS, INC.
ADJUSTMENTS
Adjustments are factory set and cannot be changed. Type 123 opens circuit as liquid
levellowersandissettocutoutatlevel“A-A”andcutinatlevel“B-B”.Type123-3
openscircuitasliquidlevelrisesandissettocutinatlevel“A-A”andcutoutatlevel
“B-B”.
Note:Notforusewithlethalorammablesubstances,eitherliquidorgaseous.
CARE OF PACKING GLAND
All low water and pump feed controls require a reasonable amount of attention to
insure dependable operation. The packing gland must be periodically tightened to
prevent leakage. Should leaks occur, screw down on knurled packing gland nut until
leakstops(usewrenchifnecessary).Nextmoveoperatingarmupanddownseveral
times by hand and then back off nut one-half turn.
When repacking of the gland is required we recommend that standard packing be
ordered from the factory.
To insure satisfactory operation at all times, this control should be checked daily. The
engineerinchargeshouldmovetheoperatingarm“D”upanddownseveraltimesby
hand,toinsurefreeoperationoftheshaft.Whenboilercompoundsareused,theoat
bowl should be blow out periodically.
CAUTION: When removing old or inserting new packing be careful not to gouge or
score the operating shaft.
WIRING
Rigid conduit must not be attached to case. Use a short strip if BX to relieve control of
conduitexpansionandcontractionstrains.WhenttingBXcableconnectorintocase,
Be careful not to damage instrument mechanism.
The lead wires should be cut short and directly connected to the terminal posts.
Excessive lengths of wire crowded into the case interfere with the free movement of
the mechanism and cause erratic operation.
Where control is directly connected into load circuit it muse be connected in hot side of
line. If in doubt as to which is the hot wire, connect one wire of a test lamp to a water
pipe,orsomeothersuitableground.Thelampwilllightwhentheotherwire(oftest
lamp)isconnectedtothehotwire.
Fuses installed in line switch should not exceed 10 amperages at 115 volts or 5
amperes at 230 volts.
ELECTRICAL RATING:
Furnishedstandardtowithstand10amp,115V,5amp,230VeitherA.C.orD.C.Motor
rating,1H.P.Repulsion-induction½H.P.SplitPhaseorD.C.
CAUTIONS-Note Carefully.
Keep cover closed and do not attempt to disconnect or change any parts. Do not
overload.Noteelectricalratingonnameplateandbesuretotalcurrentpassingthrough
switchiswithinthisrating.Donottamperwithswitchwires.Positionofthesewiresis
essential to proper operation. Tampering with these wires will void warranty.
CONTROL MOVEMENT MUSE NOT BE OILED
Note: Cold shock or water hammer must be avoided, as this condition may damage
theoatandpreventproperoperationofcontrol.
MAINTENANCE/REPAIR
Upon nal installation of the Series 123, no routine maintenance is required. The
Series123isnoteldserviceableandisnotpossibletorepairtheunit.Fieldrepair
should not be attempted and may void warranty.
WARRANTY/RETURN
Referto“TermsandConditionsofSale”inourcatalogandonourwebsite.Contact
customerservicetoreceiveaReturnGoodsAuthorizationnumberbeforeshippingthe
product back for repair. Be sure to include a brief description of the problem plus any
additional application notes.
5-1/2
[139.70]
3-9/16
[90.49]
2-7/16
[61.91]
1-1/8
[28.58]
7-1/8
[180.98]
3-11/16
[93.66]
4-7/8 [123.83]
5-37/64 [141.68]
10-29/64 [265.51]
1/2˝
CONDUIT
HOLE
Ø5-3/4
[146.05]
1/2˝
PIPE PLUG
1˝ NPT
1˝ NPT
YELLOW
[NORMALL
Y OPEN]
RED
[COMMON]
WHITE
[NORMALLY CLOSED]
USE 14 AWG 90°C COPPER CONDUCTORS ONLY
Figure 2
Typical Installation of Type 123 Low Water Control