Nordson EFD 725HF-SS Manual

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725HF-SS and 725HF-A Piston Valves
Maintenance & Parts Guide

725HF-SS and 725HF-A Piston Valves
2nordsonefd.com [email protected] 800-556-3484 Sales and service of Nordson EFD dispensing systems are available worldwide.
Valve Disassembly and
Reassembly Procedures
To prevent damage, the valve must be disassembled
starting at the uid outlet end of the valve.
CAUTION
1. Put threaded rod in mounting hole.
2. Remove body cap.
3. Remove sealing head. 
4. With a wrench on the ats of the air cylinder body,
turn to loosen uid body.
5. Remove uid body. 
6. Remove input air hose from push-in tting on air
cap.
7. Insert 1/8" hex wrench through air inlet hole in cap
and turn shaft, locking screw out two turns. 
8. Using the hex on the shaft, unthread shaft, and
remove shaft and diaphragm. 
9. Unscrew air cylinder cap from air cylinder
body. 
10. Remove piston and spring.
NOTE: Before reassembling valve, clean all parts,
replace O-rings, sealing head and diaphragm.
Inspect for damaged threads, piston pins for
straightness and uid body seat for pitting.
Do not thread uid inlet ttings too far into the valve.
Doing so can obstruct the piston shaft, causing
leakage, poor dispensing performance, and damage
to the valve.
CAUTION
Reassemble the valve in reverse order of disassembly.
Lubricate parts indicated with Nye Lubricant #865
included in the General Maintenance Kit.
O-ring only
Fluid body
#7021023
(stainless steel)
#7021040
(acetal copolymer)
Fluid tting
#7021038
Body cap
with O-ring
#7021025
(stainless steel)
#7021042
(acetal copolymer)
Sealing head
#7021026 (stainless steel)
#7021045 (PTFE-coated
stainless steel)
Shoulder “A”
Shaft
#7021029 (stainless steel)
#7021043 (PTFE-coated
stainless steel)
Diaphragm
#7020925
1
2
3
5
8

725HF-SS and 725HF-A Piston Valves
3nordsonefd.com [email protected] 800-556-3484 Sales and service of Nordson EFD dispensing systems are available worldwide.
Parts that require a specic torque when reassembling the valve.
General Maintenance Kit
#7021019 for 725HF-SS (7021020) valve
#7021016 for 725HF-A (7021015) valve†
Includes air cylinder and body cap O-rings,
diaphragm, sealing head with screw and lubricant.
†Repair kit for 725HF-A valve also includes
PTFE-coated sealing-head screws.
Maintenance Tools:
1/8" hex wrench
1/4" at-tip screwdriver
3/8" box wrench
7/8" open-end wrench
8" adjustable wrench
1/4" NPT male pipe or rod
Air cylinder
body assembly
#7020924
Push-in tting
1/8 NPT x 4 mm
(5/32")
#7021718
Nye gel lubricant, 1 gram
foil packet (not shown)
Air piston with O-ring
and shaft locking screw
#7020917
O-ring only #7014738
Shaft
locking
screw
#7014737
Air cylinder cap
with O-ring
#7020910
O-ring only
#7014735
4
6
7
9
10
725HF-SS assembly of piston,
diaphragm and shaft.
step part newton meters (inch pounds)
3 Sealing head screw 1.69 Nm (15 inch pounds)
5 Stainless steel uid body 10.8 - 13.6 Nm (8 - 10 foot pounds)
5 Acetal uid body .033 Nm (.30 inch pounds)
7 Shaft locking screw 2.82 Nm (25 inch pounds)
8 Shaft 1.69 Nm (15 inch pounds)
9 Air cylinder cap 10.8 Nm (8 foot pounds)
Thrust washer
#7014739
Spring
#7014734

For Nordson EFD sales and service in over
40 countries, contact Nordson EFD or go to
nordsonefd.com
Global
East Providence, RI USA
800-556-3484; [phone]
[email protected]
Europe
Dunstable, Bedfordshire, UK
0800 585733; [phone]
[email protected]
Asia
China: [phone]; [email protected]
India: [phone]; [email protected]
Japan: [phone]; [email protected]
Korea: [phone]; [email protected]
SEAsia: [phone]; [email protected]
©2016 Nordson Corporation 7026828 v012416
725HF-SS and 725HF-A Piston Valves
Troubleshooting Guide
No uid ow
• If valve operating air pressure is too low, the valve
will not open. Increase air pressure to 4.8 bar
(70psi) minimum.
• The reservoir air pressure may not be high
enough. Increase pressure.
• The dispensing nozzle may be clogged. Replace
nozzle.
• Fluid may have solidied in the uid body. Clean
the uid body.
Fluid drools after the valve closes,
eventually stopping
• This is caused when air is trapped in the
outlet section of the uid body or the uid has
entrapped air. The air will expand after the valve
closes, causing extrusion until the air reaches
atmospheric pressure.
• Purge the valve by dispensing at a steady
ow until clear. If a small tip is used, it may
be necessary to remove the tip while purging
to obtain sufcient ow to carry the air down
through the tip adapter.
• If the uid has entrapped air, the material must be
degassed before dispensing.
NOTE: For stripes and lines, input air pressure
can be lowered to eliminate opening surge.
Fluid drips at a steady rate after
the valve closes
• A steady drip indicates failure of the sealing
head to close fully due to particle build-up or
wear. In either case, replace the sealing head in
accordance with the maintenance instructions.
• Fluid leakage can also occur when a uid inlet
tting is threaded too far into the valve, thus
obstructing the piston shaft. Ensure that the uid
inlet tting is properly installed.
Valve responds slowly when opening and
closing
• Valve response is related to control air hose
length and size. The valve is supplied with 5-feet
of 4 mm (5/32") tubing attached. Any additional
length or size change will affect response time.
Check to be sure the length and size have not
been changed.
Fluid ows out of the drain hole
• Fluid owing out of the drain hole indicates a
ruptured diaphragm. Replace in accordance with
the maintenance instructions.
Inconsistent deposits
• Inconsistent deposits can result if the air pressure
controlling the valve and/or supplying the
reservoir is uctuating or if the valve operating
pressure is less than 4.8 bar (70 psi). Check to
be sure air pressures are constant and the valve
operating pressure is 4.8 bar (70 psi).
• The time the valve is open must be constant.
Check to be sure the valve controller is providing
a consistent output.