Pure-Flo®

72 GENERAL ENGINEERING DATA
INSTALLATION
POSITION OF DRAINABILITY
Pure-Flo Diaphragm Valves, both manual and automatic,
may be installed in either vertical or horizontal
lines to suit the application. To optimize drainability in
a horizontal line, hash marks are provided on the
casting and drain dots on the forging to orient the
valve at the proper angle during installation. This feature
helps eliminate
dangerous guess work and assures that the valve is
positioned to optimize drainability. To obtain proper
drainage, one hash mark must be in a plane cutting
the vertical centerline of the pipe. This should result
with the handwheel of the valve slightly above the
horizontal.
The slope of process piping must be designed to
provide proper pitch in order to optimize drainability.
Drainability in a process system is ultimately the
responsibility of the system designer and/or end user.
WELD INSTALLATION
Bio-Tek Valves, 1/4"–1/2" (DN 8–15) and ISO End
valves have minimum 1" (25 mm) cutbacks* and generally
do not require tube extensions for standard TIG
orbital welding equipment.
Pure-Flo Valves, 1/2"–6" (DN 15–150) can generally be
welded without tube extensions providing an “E”
(elbow) series weld head is utilized. If an “E” series
weld head is not available, then tube end extensions
are recommend
ed, and generally allow in-line welding without disassembly
using most standard TIG orbital welding
equipment.*
As an added safety precaution, a 350°F (176°C)
tempilstick should be placed on the body bonnet
flange adjacent to the weld if excessive heat transfer
is expected. The bonnet area should be kept at or
below 350°F (176°C) 1 .
DIAPHRAGM DATA
See the Pure-Flo Diaphragm section, page 22.
1 For Thermoplastic PAS Bonnets, the bonnet area should not
exceed 300°F (149°C).
* Consult factory for maximum machined cut backs.
VACUUM SERVICE
The nonporous diaphragm has low vapor pressure
and high resistance to outgassing. The design inherently
eliminates any possibility of stem leakage. Inleakage
through the standard valve is less than 0.1
micron - ft 3 /hr and on special order it can be furnished
with a substantially lower in-leak rate.
The standard Pure-Flo Diaphragm Valve is ideally
suited for vacuum service. Dependable performance
and good service life from atmospheric pressure down
to 0.1 microns make this an excellent valve for industrial
processing.
The diaphragm presents a smooth face with no hidden
voids on either side of the valve, whether open,
closed or throttling,and is bi-directional.
The vacuum chart shown on page 75 gives temperature
and pressure recommendations for PTFE
diaphragms.
The standard Pressure/Temperature recommendations
shown on page 75 should be followed when an elastomer
diaphragm is used.