Bell and Gossett DB-3/4 Operation manual

Installation, Op ration, & S rvic Instructions
SAFETY
INSTRUCTIONS
This saf ty al rt symbol will b us d in this manual to draw
att ntion to saf ty r lat d instructions. Wh n us d, th saf ty
al rt symbol m ans ATTENTION! BECOME ALERT! YOUR
SAFETY IS INVOLVED! FAILURE TO FOLLOW THESE
INSTRUCTIONS MAY RESULT IN A SAFETY HAZARD.
DESCRIPTION
Th B ll & Goss tt DB diff r ntial by-pass valv is us d in
syst ms wh r various h ating loads may b simultan ously
xclud d from th circuit b caus of th closing of control or
zon valv s.
It nsur s a r circulation proportional to th numb r of valv s
which clos , avoiding nois s and maintaining th h ad of th
pump at a constant valu .
TECHNICAL SPECIFICATIONS
Conn ctions: 3/4" x 3/4" NPT Mal
Mat rials: – Body Brass
– S als EPDM
– Spring Stainl ss St l
– Knob ABS
M dium: Wat r and glycol solutions up to 50%
Maximum Working Pr ssur : 150 PSI (10 Bar)
Maximum Working T mp ratur : 230°F (110°C)
Maximum Flow Rat : 9 GPM
Adjustm nt Rang : 2 to 10 PSI (0.15 to 0.7 Bar)
INSTALLATION INSTRUCTIONS
INSTALLER: PLEASE LEAVE THIS MANUAL FOR THE OWNER’S USE.
DB-3/4"
Diff r ntial By-Pass Valv
3/4" x 3/4" NPT Mal Conn ctions
Op rational Limits
Bell & G ssett
Instruction Manual A91590
REVISION A
Max. T mp ratur 230°F (110°C)
Max. Pr ssur 150psig (10 Bar)
NOTE: This pr duct is n t intended f r use in p table
water applicati ns.
WARNING: Syst m fluids ar und r pr ssur or t mp-
ratur can b hazardous. B sur th pr ssur has
b n r duc d to z ro and th syst m t mp ratur is b low
100°F (38°C). Failur to follow th s instructions could r sult
in prop rty damag and/or p rsonal injury.
WARNING: State f Calif rnia Residents
This product contains a ch mical known by th Stat
of California to caus canc r. This products contains a
ch mical known by th Stat of California to caus birth
d f cts or oth r r productiv harm.
CAUTION: All work must b p rform d by qualifi d
p rsonn l train d in th prop r application, installation,
and maint nanc of syst ms in accordanc with all applica-
bl cod s and ordinanc s.

INSTALLATION INSTRUCTIONS (c nt'd) INSTALLATION INSTRUCTIONS (c nt'd)
Th by-pass valv should b install d aft r th pump b tw n
th supply and r turn piping. It can b install d ith r in th hor-
izontal or v rtical position provid d it is in accordanc with th
dir ction of flow as indicat d by th arrow on th valv body
(s Figur 1). With all valv s op n, s t th bypass valv to
maximum pr ssur (clockwis ). Gradually op n th bypass
valv (count rclockwis ) until flow b gins in th bypass valv .
Incr as th pr ssur s tting by 1/2 to 1 psi or turn knob clock-
wis 1/2 r volution so th wat r stops flowing through th
bypass valv .
OPERATING INSTRUCTIONS OPERATING INSTRUCTIONS
Turn th knob to th d sir d valu of th graduat d scal ; th
valu s corr spond to th discharg pr ssur of th pump. Lock
th s tscr w locat d on th knob.
CAUTION: Mak sur that all th conn cting pip work
is wat r tight.
CAUTION: If th by-pass valv is not install d, com-
mission d and maintain d prop rly, according to th
instructions contain d in this manual, it may not op rat cor-
r ctly and may ndang r th us r.
SERVICE INSTRUCTIONS
Th r is no s rvic r quir d for th diff r ntial by-pass valv .
CAUTION: Corrosion or l akag of th diff r ntial by-
pass valv can caus damag or injury, P riodically
insp ct th diff r ntial by-pass valv for signs of l akag or
corrosion. If not d, th diff r ntial by-pass valv must b
r plac d. Failur to follow th s instructions could r sult in
prop rty damag and/or mod rat p rsonal injury.
CAUTION: Ov rtight ning and br akag can occur
with th us of T flon®pip joint compounds. T flon®
provid s lubricity so that car must b x rcis d not to ov r
tight n joints. Failur to follow th s instructions could r sult
in prop rty damag and/or mod rat p rsonal injury.
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TYPICAL INSTALLATION
FIGURE 1
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