MKS HPS Square Body LoPro Series User manual

HPS®Square Body LoPro Series
Bellows Sealed Poppet Valves
OPERATION AND
MAINTENANCEMANUAL

HPS®Square Body LoPro Series
May 1999
PART #100010482
HPS®Square Body LoPro Series
Bellows sealed Poppet Valves

HPS®Square Body LoPro Series
Part # __ - __ __ __ __
Please fill in these numbers and have them readily
availablewhencallingforserviceoradditional
information.
(The part number is located on the label attached to a
cableoftheheater.)
© 1999 by Vacuum Products Group of MKS Instruments, Inc. All rights reserved.
ALCONOXisaregisteredtrademarkofAlconox,Inc.
IgniTorris atrademark ofHPSTM Division ofMKS Instruments,Inc.
InconelisaregisteredtrademarkofIncoAlloysInternational,Inc.
Scotch-Briteisatrademarkof3M.
SensaVacisaregisteredtrademarkofMKSInstruments,Inc.
For more information or literature, contact:
Vacuum Products Group of MKS Instruments, Inc.
5330 Sterling Drive
Boulder, CO 80301 USA
Phone: [phone]
800-345-1967
FAX: [phone]

HPS®Square Body LoPro Series
Table of Contents
Table of Contents
1.Package Contents.................................................................. 1
1.1 INTHIS MANUAL................................................................................ 1
1.2 Symbols Used in this Manual.............................................................. 1
2. Safety Precautions................................................................. 2
Modification .............................................................................................. 2
Maintenance ............................................................................................. 2
HazardousMaterials ................................................................................. 2
Installation ................................................................................................ 2
Operation .................................................................................................. 2
3. Description of LoPro Valves................................................... 3
4. Operating Principles .............................................................. 5
4.1PneumaticVersion .............................................................................. 5
4.1.1 Pneumatic Cycling .................................................................................................. 5
4.1.2 Limit Switch Actuation ............................................................................................. 7
4.1.3 Solenoid Operated Pilot Valve Operation ............................................................... 8
4.2ManualVersion.................................................................................... 9
4.2.1 Manual Cycling........................................................................................................ 9
5. Specifications ...................................................................... 11
5.1Environment...................................................................................... 11
5.1.1 Installation Orientation .......................................................................................... 11
5.1.2 Applied Forces ...................................................................................................... 11
5.1.3 Temperature Extremes ......................................................................................... 11
5.2Operation& Performance .................................................................. 13
5.2.1 Cycle Rate and Life .............................................................................................. 13
5.2.1.1 Pneumatic Actuation ............................................................................... 13
5.2.1.2 Manual Actuation .................................................................................... 13
5.2.2 System Pressure Limits ....................................................................................... 13
5.2.3 Pneumatic Pressure Limits – Pneumatic Actuation Only.................................... 14
5.2.4 Pneumatic Flow–Pneumatic Actuation Only ........................................................ 14
5.2.5 Limit Switch Ratings– Pneumatic Actuation Only ................................................ 14
5.2.6 Solenoid Duty Cycle and Power Requirements................................................... 14
5.3 Dimensions ....................................................................................... 15
5.3.1 Dimensions – Manual Actuation ........................................................................... 15
5.3.2 Dimensions – Pneumatic Actuation ..................................................................... 17
5.3.3 Weight ................................................................................................................... 19
6.InstallationInformation......................................................... 20
6.1 Pneumatic Supply– Pneumatic Actuation Only ................................. 20
6.2 Electrical Connections– Pneumatic Actuation Only........................... 20
6.3CleanInstallation .............................................................................. 21
6.4FlangeCare ...................................................................................... 21

HPS®Square Body LoPro Series
7.3 Actuator Assembly - ManualVersion................................................. 23
7.3.1 Actuator Assembly Removal and Disassembly .................................................. 23
7.3.2 O-Ring Replacement ............................................................................................ 24
7.3.3 Actuator Assembly Installation ............................................................................. 24
7.4 Limit Switches - Pneumatic Actuation Only ...................................... 25
7.4.1 Limit Switch Removal............................................................................................ 25
7.4.2 Limit Switch Installation ......................................................................................... 25
7.4.3 LS Retrofit ............................................................................................................. 25
7.5 Solenoid PilotValve Service - Pneumatic Actuation Only.................. 26
7.6 Replacement Parts List..................................................................... 28
8.Trouble Shooting.................................................................. 29
8.1Problems and Diagnosis Pneumatic Actuation .................................. 29
8.1.1 Won't close completely ......................................................................................... 29
8.1.2 Won't open completely.......................................................................................... 29
8.1.3 Opens slowly or in jumps ..................................................................................... 29
8.1.4 Won't open at all .................................................................................................... 30
8.1.5 Squeaks When opening and /or closing .............................................................. 30
8.1.6 Leaks across closed nosepiece seal .................................................................. 30
8.1.7 Leaks from atmosphere when closed ................................................................. 30
8.1.8 Leaks from atmosphere when open .................................................................... 31
8.1.9 Leaks from atmosphere at all times ..................................................................... 31
8.1.10 Air leaks from around piston when open ........................................................... 31
8.1.11 Air leaks from vent hole while opening............................................................... 31
8.1.12 Air leaks from vent hole when open................................................................... 31
8.1.13 Limit switches not sending signals..................................................................... 31
8.1.14 Solenoid valve buzzes or doesn't work ............................................................. 31
8.2ProblemsandDiagnosisManualActuation ....................................... 32
8.2.1 Won't close completely ......................................................................................... 32
8.2.2 Won't open completely.......................................................................................... 32
8.2.3 Difficult to open/close or Squeaks........................................................................ 32
8.2.4 Leaks across closed nosepiece seal .................................................................. 32
8.2.5 Leaks from atmosphere when closed ................................................................. 32
8.2.6 Leaks from atmosphere when open .................................................................... 33
8.2.7 Leaks from atmosphere at all times ..................................................................... 33
8.3CausesandRemedies ...................................................................... 33
8.3.1 Spring failure - Pneumatic Actuation Only ........................................................... 33
8.3.2 Body damage ........................................................................................................ 33
8.3.3 Port flange damage ............................................................................................... 33
8.3.4 Particulates, condensation, and corrosion .......................................................... 34
8.3.5 Bellows failure ....................................................................................................... 34
8.3.6 Nosepiece seal failure .......................................................................................... 34
8.3.7 Bonnet seal failure ................................................................................................ 34
8.3.8 Piston seal failure - Pneumatic Actuation Only.................................................... 34
8.3.9 Stem seal failure - Pneumatic Actuation Only ..................................................... 35
8.3.10 Bonnet seal omission.......................................................................................... 35
8.3.11 Nosepiece seal omission ................................................................................... 35
8.3.12 Improper assembly............................................................................................. 35
8.3.13 Loose piston hold down screw - Pneumatic Actuation Only............................. 35
8.3.14 Inadequate Lubrication ....................................................................................... 36
8.3.15 Inadequate air pressure - Pneumatic Actuation Only ....................................... 36
8.3.16 Inadequate air flow - Pneumatic Actuation Only................................................ 36
8.3.17 Limit switch failure - Pneumatic Actuation Only................................................. 37
8.3.18 Solenoid valve failure - Pneumatic Actuation Only ............................................ 37
8.3.19 Stem Weld Failure ............................................................................................... 37

HPS®Square Body LoPro Series
7. SERVICE............................................................................. 22
7.1 Removal from System ...................................................................... 22
7.1.1 Pneumatic Version ..................................................................................... 22
7.1.2 Manual Version ........................................................................................... 22
7.2 Actuator Assembly – PneumaticVersion .......................................... 23
7.2.1 Actuator Assembly Removal and Disassembly ....................................... 23
7.2.2 O-Ring Replacement ................................................................................. 23
7.2.3 Actuator Assembly Installation .................................................................. 24
7.3 Actuator Assembly – ManualVersion................................................ 24
7.3.1 Actuator Assembly Removal and Disassembly ....................................... 24
7.3.2 O-Ring Replacement ................................................................................. 25
7.3.3 Actuator Assembly Installation .................................................................. 25
7.4 Limit Switches – Pneumatic Actuation Only...................................... 26
7.4.1 Limit Switch Removal................................................................................. 26
7.4.2 Limit Switch Installation .............................................................................. 26
7.4.3 LS Retrofit .................................................................................................. 26
7.4.4 Limit Switch Adjustment ............................................................................. 27
7.5 Solenoid PilotValve Service – Pneumatic Actuation Only................. 27
7.6 Replacement Parts List..................................................................... 29
8.Trouble Shooting.................................................................. 30
8.1Problems and Diagnosis Pneumatic Actuation .................................. 30
8.1.1 Won’t close completely .............................................................................. 30
8.1.2 Won’t open completely............................................................................... 30
8.1.3 Opens slowly or in jumps .......................................................................... 30
8.1.4 Won’t open at all ......................................................................................... 31
8.1.5 Squeaks when opening and/or closing ..................................................... 31
8.1.6 Leaks across closed nosepiece seal ....................................................... 31
8.1.7 Leaks from atmosphere when closed ...................................................... 31
8.1.8 Leaks from atmosphere when open ......................................................... 32
8.1.9 Leaks from atmosphere at all times .......................................................... 32
8.1.10 Air leaks from around piston when open ................................................ 32
8.1.11 Air leaks from vent hole while opening.................................................... 32
8.1.12 Air leaks from vent hole when open........................................................ 32
8.1.13 Limit switches not sending signals .......................................................... 32
8.1.14 Solenoid valve buzzes or doesn’t work .................................................. 32
8.2ProblemsandDiagnosisManualActuation ....................................... 33
8.2.1 Won’t close completely .............................................................................. 33
8.2.2 Won’t open completely............................................................................... 33
8.2.3 Difficult to open/close or Squeaks............................................................. 33
8.2.4 Leaks across closed nosepiece seal ....................................................... 33
8.2.5 Leaks from atmosphere when closed ...................................................... 33
8.2.6 Leaks from atmosphere when open ......................................................... 34
8.2.7 Leaks from atmosphere at all times .......................................................... 34
8.3CausesandRemedies ...................................................................... 34
8.3.1 Spring failure – Pneumatic Actuation Only................................................ 34
8.3.2 Body damage ............................................................................................. 34
8.3.3 Port flange damage .................................................................................... 34
8.3.4 Particulates, condensation, and corrosion ............................................... 35
8.3.5 Bellows failure ............................................................................................ 35
8.3.6 Nosepiece seal failure ............................................................................... 35
8.3.7 Bonnet seal failure ..................................................................................... 35
8.3.8 Piston seal failure – Pneumatic Actuation Only ........................................ 35
8.3.9 Stem seal failure – Pneumatic Actuation Only .......................................... 36
8.3.10 Bonnet seal omission............................................................................... 36
8.3.11 Nosepiece seal omission......................................................................... 36
8.3.12 Improper assembly.................................................................................. 36
8.3.13 Loose piston hold down screw –............................................................. 36
8.3.14 Inadequate lubrication.............................................................................. 36

HPS®Square Body LoPro Series
8.3.15 Inadequate air pressure – Pneumatic Actuation Only............................ 37
8.3.16 Inadequate air flow – Pneumatic Actuation Only .................................... 37
8.3.17 Limit switch failure – Pneumatic Actuation Only ..................................... 37
8.3.18 Solenoid valve failure – Pneumatic Actuation Only ................................ 37
8.3.19 Stem Weld Failure .................................................................................... 38
9. RETURN TO FACTORY FOR REPAIR OR SERVICE ........ 39
9.1 Call the factory.................................................................................. 39
9.2Prepareforshipment......................................................................... 39
10.ProductWarranty................................................................ 40
11.Notes ................................................................................. 42

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The first two symbols below, that may be located on your HPS®Square Body
LoPro Series, identify critical safety concerns. They are used throughout this
manual to further define the safety concerns associated with the product.
CAUTION: Risk of electrical shock.
CAUTION: Refer to manual. Failure to heed message
could result in personal injury or serious damage to the
equipment or both.
The last two symbols identify other information in this manual that is
essential or useful in achieving optimal performance from the PDR 9000.
Failure to heed message could result in damage
to the equipment.
Calls attention to important procedures, practices,
or conditions.
1.Package Contents
1.2 Symbols Used in this Manual
(Telephone [phone]
Toll-Free [phone] (USA only)
Facsimile [phone]
MKS Instruments, Inc.
Vacuum Products Group
5330 Sterling Dr.
Boulder, CO. 80301
USA
1.1 INTHIS MANUAL
Thismanualdetails functional informationforthenon-heatedHPS®Square
Body LoPro Series, angle and in-line bellows sealed poppet valves, their
options and accessories. HPS®also offers a Square Body LoPro heated
valve line, the Jalapeno LoPro Series. For more information on the Jalapeno
LoProseriesrefertoJalapenoLoProinstructionmanual.
Inspect the Square Body LoPro for visible evidence of damage during
shipment. If it has been damaged, notify the carrier immediately. Keep all
shipping materials and packaging for claim verification. Do not return the
Product to HPS®.

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Modification
Unauthorizedmodificationoftheproductvoidsthewarrantyand
may affect its operation. Contact HPS® Applications Engineering
Department for more information on customizing your valve.
Maintenance
Install only HPS®replacement parts or their equivalents following
the procedures detailed in section 7.
Hazardous Materials
If hazardous materials are used, users must take responsibility to
observe the proper safety precautions and insure that the material
used is compatible with those from which the valve is fabricated.
Installation
All flanges and fittings interfacing with the valve must be consistent
with those on the valve. Assemble and tighten vacuum flanges and
pneumatic fittings according to standards and carefully check for
leaks prior to operation. Pneumatic valves with solenoid pilot valves
and/or limit switches should be properly grounded.
Operation
Keep fingers, clothing, hair, and other intrusive materials away from
the valve ports during operation. Never exceed the upper limits for
internal or pneumatic pressure. If equipped with solenoid pilot valve
or limit switches, do not operate in explosive atmospheres.
2. Safety Precautions

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HPS®Square Body LoPro valves are pneumatically or manually operated
bellows sealed poppet valves, designed for compact size, lightweight, and
long life.
Internal actuation in the pneumatic version of the Square Body LoPro valve
is controlled by a pneumatic cylinder attached directly to the top of the
valve. The valve is opened when pneumatic pressure is supplied to the
bottom of this cylinder. When the air is vented, the valve is closed by an
internal spring. In the event of a power or pneumatic failure, the valve
returns to its closed position.
Internal actuation in the manual version of the Square Body LoPro valve
is controlled by a knob located on the top of the valve. The valve is
opened when the knob is turned counter clockwise to the topped out
position. The valve is closed when the knob is turned clockwise to the
bottomed out position.
The bodies of both the pneumatic and manual versions of the valve are
available in angle and concentric in-line configurations with a variety of
flanging. Custom body configurations and flange combinations are available
upon request.
O-rings function as face seals on the bonnet and nosepiece, while a metal
bellows is used to seal the moving poppet. O-rings are available in a
variety of elastomers.
Optional limit switches for the remote indication of open and closed
positions are available for the pneumatic version only. These limit switches
are mounted on the top of the cylinder and are directly actuated by a cam
extending from the upper end of the stem.
A solenoid operated pneumatic pilot valve may, optionally, be installed in
the pneumatic version only. This pilot valve allows electrical control of the
Square Body LoPro valve while it is connected directly to the facility
pneumatic supply. Solenoid valves are available in a variety of voltages.
3.Description of
LoPro Valves

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Figure 1 Square Body LoPro Valve Options
LPV1- 25- A K- CN V S- 12D
Square Body Low Profile Valve Series
25 = 25mm (1.0") nominal size
40 = 40mm (1.5") nominal size
50 = 50mm (2.0") nominal size
A = Angle body
I = Concentric in line body
K = ISO KF flanges
C = CF flanges
T = Butt weld tubes
CN = Normally closed, no limit switch
CL = Normally closed, with limit switch
MN = Manual actuation
B = Buna - N o-rings
E = EPDM o-rings
K = Kalrez o-rings
S = Silicone o-rings
V = Viton o-rings
Z = Chemraz o-rings
S = Standard temperature range
N = Manual actuation
Blank = No solenoid
12D = 120 VDC
24A = 24 VAC 50/60 Hz
24D = 24 VDC
100 = 100 VAC 50 Hz
120 = 120 VAC 50/60 Hz
208 = 208 VAC 50/60 Hz
240 = 220 VAC 50/60 Hz
PNF=Custom
SPD=Custom
SPN=Custom
Figure 1 Summarizes the options available for the Square Body LoPro
Series.

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4.1 Pneumatic Version
Figure 2 - Pneumatic operation
4.1.1 Pneumatic Cycling
Figure 2 illustrates the components of the pneumatic valve. From its
normally closed position, the valve is opened with the admission of
compressed air to the pneumatic cylinder through the 1/8" female NPT port
in the side of the cylinder (1).
4. Operating Principles
Actuator Cylinder 1
Piston 2
O-Ring 11
Bellows 4
Spring Bushing 5
Nosepiece 7
Seat 8
14 Flat Head Screw
15 Piston Seal
13 Stem Seals
12 Rulon Bearing
3 Spring
10 Body
9 O- Ring

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When the pneumatic pressure in the cylinder reaches a value sufficient to
overcome the force of the spring (3), the piston (2) starts to rise, pulling
the nosepiece (7) off of the seat (8). The stem (6) is attached to the piston
with a flat head screw (14). The actuator cylinder is vented to allow air
from within the bellows (4) to escape (and enter) as its volume changes. At
the lower end of the stem, the nosepiece is welded to the stem. It carries
ano-ring seal (9) in a trapezoidal groove, which, whensqueezedbetween
the nosepiece and the seat, effects the seal at the valve orifice. The
bellows forms a flexible hermetic seal between the nosepiece and the fixed
elements of the body (10).
As long as adequate pneumatic pressure is applied, the piston continues to
travel upward, further compressing the spring, until the top of the
nosepiece, spring bushing (5), and bottom of the cylinder are all in contact.
This is the open position stop.
To close the valve, the cylinder is vented through the same 1/8" NPT
port. As the air pressure falls below the value necessary to maintain
compression on the spring at the open position stop, the piston and the
nosepiece start to move towards the closed position. As venting
continues, the nosepiece and seal reach the seat. After the valve is
closed, full seal force is not attained until the cylinder has reached
minimum (usually atmospheric) pressure.

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Figure 3 - Limit switch operation
4.1.2 Limit Switch Actuation
When a valve is equipped with limit switches, they are mounted on top of
the cylinder as shown in Figure 3. When the valve is closed, the lever of the
closed position switch (18) is depressed by the cam extension (17) on the
top of the stem (6). When the valve is fully opened, the cam extension
activates the lever of the open position switch (16).
Observing that the closed position limit switch is actuated does not
necessarily verify that the valve is sealed leak tight, as contamination or
damage to the seal or seat could affect seal integrity. It does confirm,
however, that the valve, and its control, obeyed the command to move to
the closed position.

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4.1.3 Solenoid Operated Pilot Valve Operation
Optional installation of a solenoid operated pneumatic pilot valve in the 1/8"
female NPT port in the side of the cylinder (1), as shown in Figure 4,
enables remote electrical control of the valve when direct pneumatic control
is inconvenient. In its de-energized state, this 3-way valve vents the cylinder
of the Square Body LoPro through a threaded hole centered in the top of
the solenoid coil (20). A nipple (24) connects the 1/8" female NPT outlet
port on the solenoid valve to the cylinder of the Square Body LoPro. The
joints are sealed with an anaerobic pipe compound.
When power is applied, the magnetic field developed by the coil overcomes
the force of the spring (22) and lifts the plunger (21) off the seat (23). While
this opens a pressurized flow path from
the pneumatic line connected to the 1/8"
NPT inlet port, it also seals the venting
flow path. Being at the vent port’s
pressure (usually, but not necessarily
atmospheric), the cylinder of the valve is
quickly pressurized and the valve opens
(see section 3.1).
When power to the solenoid is turned off,
the spring forces the plunger back to its
original position, simultaneously closing
the pressurized port and opening the
vent port. Pressurized air in the cylinder
of the valve quickly escapes through
grooves on the outside of the plunger
and out the vent port, allowing the valve
to close (see section 3.1).
Users may supply their own solenoid
operated pilot valve. A solenoid valve
rated for > 106cycles continuous duty
and a conductance > .05 in3/min is
recommended. The lengths and
diameters of pneumatic feed lines
must also be considered for peak performance. Figure 4 - Solenoid pilot valve

9
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4.2 Manual Version
4.2.1 Manual Cycling
Figure 5 illustrates the components of the manual valve. From the closed
position, the valve opens by twisting the manual knob counterclockwise,
raising the manual screw in the manual stem guide thus lifting the
nosepiece off of the seat. The manual stem guide has a vent to allow air
from within the bellows to escape (and enter) as its volume changes. The
top of the stem is attached to the manual screw via a pan head screw,
while the bottom of the stem is welded to the nosepice. The nosepiece
carries an o-ring seal in a trapezoidal groove, which, when squeezed
between the nosepiece and the seat, effects the seal at the valve orifice.
The bellows forms a flexible hermetic seal between the nosepiece and the
fixed elements of the body. The open position stop occurs when the top of
the thrust bearing and the bottom of the stem guide are in contact.
To close the valve, simply turn the manual knob all the way in the clockwise
direction. The valve is not closed until the nosepiece and seal are in
contact with the seat and full seal pressure is applied.
4.2 Manual Version

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Figure 5
LPV! - 25 Manual Actuation Angle KF
Manual Knob
Manual Stem Guide
Body Flange
Bellows
Thrust Bearing
Nosepiece O - Ring
Nosepiece
Manual Screw
Bellows Flange
Body
Stem

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Square Body LoPro Series valves function equally well installed in any
orientation.
5.1.2 Applied Forces
As with any vacuum piping component, improper installation in the vacuum
line may result in damage to the component. The strength of the Square
LoPro body is roughly equivalent to an elbow of similar size. Care must be
taken to protect the body of the Square LoPro from excessive stress buildup
in the vacuum line. This problem may be avoided by the proper installation
of flexible metal hose(s). The HPS® Applications Engineering department is
available to help with such problems.
5.1.3 Temperature Extremes
The Square Body LoPro valve series is rated for service from -20oC to 93oC
(standard manual version, pneumatic version without the optional limit
switch package or solenoid operated pilot valve). In the pneumatic version,
addition of the optional limit switch package decreases the upper
temperature limit to 82oC, while adding the optional solenoid pilot valve
increases the lower limit to 0oC.
The Square Body LoPro valve’s most vulnerable components to
temperature extremes are the organic compounds used in seals, bearings,
and lubrication. In the pneumatic version, the pressurized cavity in the
pneumatic cylinder is sealed by a pair of Parker PolyPak1Seals. These
standard temperature range seals are rated for service from -51oC to
93oC2.(Reference Figure 2, p.5 for Lopro intrnal schematic)
O-rings in Figure 2 seal the bonnet and poppet of the valve and are
available in a variety of seal elastomers. These elastomers have the
following recommended operating temperature ranges3:
Buna-N -54oC to 135oC
Kalrez4-26oC to 260oC
Silicone -114oC to 232oC
Viton4-26oC to 204oC
Excessive temperatures, especially in combination with dry air or gas, can
cause o-rings and seals to dry out, harden, crack, or even melt, possibly
resulting in a vacuum or pneumatic leak. However, because the transfer of
5. Specifications
5.1 Environment
5.1.1 Installation Orientation

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heat from/to the valve’s pneumatic actuator assembly to/from the body and
the nosepiece of the valve is relatively inefficient, the nosepiece o-ring may
be subjected to significantly higher/lower temperatures without affecting the
pneumatic seals. However, to avoid pneumatic seal damage, the cylinder
temperature should be monitored in the presence of sustained extreme
system or ambient temperatures.
The Rulon LR5PTFE bearings supporting the stem are rated for service
between -240oC and 287oC6. Lubricating greases used on the stem, piston
seal, and manual screw increase their viscosity at low temperatures. This
increase in viscosity increases the force required to move the poppet.
Lighter fractions of these lubricants begin to evaporate at temperatures
below 100oC, ultimately resulting in dried lubricant, increased friction on the
sliding surfaces, and also increasing the force required to move the poppet.
While the operating temperatures of these lubricants do not pose immediate
problems, regular maintenance, with attention to the condition of the piston,
stem and manual screw lubricants, should be performed on valves run for
extended periods at or near the high temperature limit.
Similarly, the optional limit switch package contains polymers and
elastomers in the switch housings and grommets. The temperature ratings
for these components are as follows7:
Switches -53oC to 85oC
grommets -51oC to 82oC
The wire or cable connected to the limit switches and/or solenoid valve
should be selected for use in the appropriate temperature range.
Optional solenoid operated pneumatic pilot valves also have organic
compounds in their seals and in the insulation of the coil and lead wires. All
Peter Paul solenoid valves normally supplied with Square Body LoPro
valves are rated for operation between 0oC and 104oC.
1) Polypak is the registered trademark of the Parker Hannifin Corp.
2) PolyPak Seal Design Handbook, 2, (1989)
3) Parker O-Ring Handbook, A3-4 / A3-6, (1991)
4) Kalrez and Viton are the registered trademarks of E.I. du Pont de Nemours Co.
5) Rulon is the registered trademark of Kixon, Division of Furon
6) Guide to dexon Bearings D4
7) Courtesy of Microswitch Division of Honeywell Corp.