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PIONEER INDUSTRIAL CO
PIONEER
INDUSTRIAL
CO., LTD
SPECIALIZED IN PRESSURE GAUGES
Pressure Gauge Installation,
Operation & Maintenance
Pressure Gauge Operating
Principle
Most standard dial type pressure gauges use a
bourdon tube-sensing element generally made of a copper alloy (brass) or
stainless steel for measuring pressures 15 PSI and above. Bourdon tube gauges
are widely used in all branches of industry to measure pressure and vacuum. The
construction is simple yet rugged and operation does not require any additional
power source. The C-shaped or spirally wound bourdon tube flexes when pressure
is applied producing a rotational movement, which in turn causes the pointer to
indicate the measured pressure. These gauges are generally suitable for all
clean and non-clogging liquids and gaseous media. Low pressure gauges typically
use an extremely sensitive and highly accurate capsule design for measuring
gaseous media from as low as 15 INWC to 240 INWC (10 PSI). Digital gauges use an
electronic pressure sensor to measure the pressure and then transmit it to
digital display readout.
Selecting a Pressure Gauge
I t is
important to consider the various information outlined in this manual to ensure
appropriate pressure gauge selection and usage. Improper application can lead to
instrument failure and possible personal injury and/or property damage. The
following information in this manual is meant to be a guide in the selection
process. Please feel free to consult Pioneer Instruments for further assistance
and clarification.
Types of Pressure Gauges
Pioneer offer a full range of pressure gauges suitable for virtually all types
of applications. Some specific types of pressure gauges that will be covered in
this manual are general-purpose Bourdon tube, capsule-type, Precision test
pressure gauge, Diaphragm Pressure Gauges
*General-Purpose Bourdon Tube Gauge
This
common type of gauge utilizes a C-Bourdon tube, which usually has an arc of 250
degrees. The process pressure is connected to the fixed socket end of the tube,
while the tip end is sealed. Because of the difference between inside and
outside radii, the Bourdon tube tends to straighten when pressure is applied.
The non-linear motion at the tip of the Bourdon tube is converted to linear
rotational pointer response through the use of gears and pinion movement. This
type of pressure gauge is used in medium to high-pressure measurements with
accuracies of 0.1 to 3% of full span. The pressure range capabilities start from
15 psi (100 kPa) to 20,000 psi (137.8 Mpa).
*Capsule-Type Gauge
Capsule-type are formed from welding two pre-formed plates together. Input
process pressures cause the capsule to expand or contract which is then
translated into a linear rotational pointer response through the use of gears
and pinions. Bellows gauges are typically used in low to intermediate and vacuum
pressure ranges with 0.1 to 1% of full span accuracy. Pioneer Instruments
capsule gauges have pressure ranges from 0-15" H2O (0-3.7 kPa) to 0-10 psi
(0-68.9 kPa).
*Differential Gauges
he
purpose of a differential gauge are similar to a duplex gauge, but this gauge
will indicate the difference between two related pressures. Pioneer Instruments
provide three different types of differential gauges; parallel Bourdon tube,
magnet and piston, and opposing Bourdon tube designs.
*Diaphragm Pressure Gauges
he
design principle and the material selection of pressure gauges allow them to
meet the stringent demands occurring in service and industrial processing
plants. Diaphragm pressure gauges have a relatively high actuating force. The
annular clamped diaphragm is Insensitive to jarring or vibration. An extremely
high resistance to overpressure is achieved by under propping the diaphragm.
Special corrosion resistant materials protect the wetted parts in service with
chemically aggressive media. Open process connections ensure that the pressure
gauges are easy to clean (e. g. by rinsing) even with highly viscous,
crystallizing process media and with Media with highly heterogeneous
composition.Ranges:-1 ...0 bars to 0 ... 25 bar. Applications: Mechanical
engineering, plant and machinery construction. Features: Sturdy aluminum and
stainless steel housing; Corrosion resistance from special materials; High
resistance to overpressure; particularly suitable for highly viscous; and
crystallizing media; Protection IP 54
*Precision test pressure gauge
these
test pressure gauges are manufactured to the very highest standards and are used
to test pressures of tanks, pipes fittings and in laboratories. The precision
test pressure gauges have a high-grade measuring element. The pressure
proportional elastic deformation of the Bourdon tube is transmitted through a
low friction movement to the knife edge pointer. The gauges can be used with non
aggressive gaseous or liquid, but not with highly viscous or crystallizing
media. The measuring accuracy can be certified by the manufacturer in accordance
with DIN 55 350 part 18 at additional cost. Ranges 0... 0.6 bar to 0 ...1600 bar
Applications：Precision
monitoring in processing plants, control and adjustment of pressure gauges, test
equipment etc.
*Pressure gauges with electric Contact
Contact pressure gauges with electrical alarm contacts are suitable for
controlling or regulating process sequences with the aid of the process
pressure. The contacts open or close electrical circuits in relation to the
position of the Pointer on the pressure gauge. Contact pressure gauges with the
Bourdon tube system are used at process pressures of approximately 1 bar and
upwards. The media, gases or liquids, should not however corrode the
copper-alloy materials used. Liquids should not be too viscous or tend to
crystallized. The inexpensive and tested Bourdon tube system coupled with a
modern modular principle provides a very reliable yet inexpensive contact
pressure gauge. Gauges with filling are damped if pressure pulses or mechanical
vibrations occur. This prolongs the service life and the gauge display remains
largely vibration free. The location of the pressure connection at the bottom or
back allows different methods of installation. Electric alarm contacts are used
as magnetic snap-action contacts, especially in harsh industrial conditions. The
high contact pressure and the choice of different electrical contact materials
enable high currents to be switched reliably. If the electrical switching
capacity of the alarm contacts is exceeded or not reached, a relay is to be used
to provide an appropriate current rating. Inductive alarm contacts operate
without physical contact and thus have no unfavorable effects on the pressure
measuring system while having an unlimited service life. A control unit is
always needed to operate these contacts. Contact pressure gauges with inductive
alarm contacts can be used in potentially explosive atmospheres, provided that
the appropriate regulations are complied with. Features；High
reliability and durability；Vibration-free
indication by fluid damping；
Protection IP 54 / IP65；
Accuracy class 1.0；Housing
made of stainless steel；Movement
brass；Up
to four alarm contacts possible. Ranges 0...1 bar to 0 ...1000 bar Applications
Process engineering, mechanical engineering and plant construction, water
treatment, hydraulic and pneumatic systems.
*Parallel Bourdon Tube Differential Gauge
he
placement of the Bourdon tubes is similar to that of the duplex gauges. The
gears and pinions are calibrated to measure the difference between the flex of
the two Bourdon tubes and this is translated to a single pointer. This type of
differential gauge is used when the indicating scale is 2/3 of the process
static pressure due to the limitations of the Bourdon tubes.
Pressure Range
Select
a pressure gauge with a full-scale pressure range of approximately twice the
normal operating pressure. For Bourdon tube gauges, the maximum operating
pressure should not exceed 75% of the full-scale range. The exception to this
rule is the opposing Bourdon tube differential gauge. Failure to select a gauge
within these criteria may result in premature fatigue and failure of the Bourdon
tube.
Temperatures
The
normal ambient temperature ranges are -40C to 70C (-40F to 158F) for dry gauges
and -25C to 65C (-13F to 149F) for glycerin filled gauges. The process
temperature for dry gauges can be up to 400C (752F). In situations where the
process temperature is extreme, utilizing a syphon or remote mounting the
pressure gauge with a capillary and diaphragm seal are reasonable alternatives.
In general, a gauge is unduly hot if it cannot be grasped by hand without
discomfort. It should be noted that gauges used on water might burst if exposed
to frost. Please consult Pioneer for your specific requirements.
Materials
Winters provide a full range of casing and wetted parts to accommodate all types
of applications. The most common wetted parts used are brass and 316stainless
steel. Brass wetted parts are suitable for use on the following types of media;
air; oil, water and other non-corrosive fluids. For corrosive fluids, stainless
steel should be specified. For special applications, other materials such as
Monel can be used as well. Diaphragm seals may also be considered. Please
consult Pioneer Instruments for assistance.
Vibrations
Vibrations and extreme ambient temperatures can affect the dial reading of the
pressure gauges. These areas should be avoided as much as possible. Vibration
effects can be minimized by the use of a dampening liquid such as glycerin or
silicone. If vibration is extreme, then a flexible tube connected to an
appropriate diaphragm seal should be considered.
Pulsations
f
pressures are expected to pulsate violently, oscillate with high frequency or
occur with sudden shock, a snubber should be considered. Pioneer snubbers
incorporate sintered porous 316 stainless steel snubbing element with a large
surface area to ensure long term effectiveness on most pressure media. Snubbers
are available in the three viscosity classifications; heavy oil, water and air.
Brass, stainless steel or Monel housing can be specified depending upon the
media used.
Isolating Valves
It is
recommended that isolating valves be fitted with the gauge. This enables the
gauge to be removed at any time for checking, recalibration or replacing without
interruption to the process. The valves should be opened or closed slowly to
avoid sudden changes to pressure being applied to the gauge. It is recommended
for systems that have an abrupt pressure surge at start-up to close the valves
during initial start-up.
Pressure Gauge
Installation
Location
vibrations and extreme ambient temperatures can affect the dial reading of the
pressure gauge. These areas should be avoided as much as possible. Vibration
effects can be minimized by the use of a dampening liquid such as glycerin or
silicone. If vibration is extreme, then a diaphragm seal connection should be
considered.
Mounting
suitable thread sealant is required for N.P.T. threads such as pipe dope or
Teflon tape. Never use any part of the pressure gauge other than the wrench
flats that is on the gauge socket. Always tighten with an open end or adjustable
wrench on the wrench flats. Failure to do so will severely damage the pressure
gauge. Please note the following special requirements for the piston
differential gauge.
Venting Procedures
Due
to pressure “build up”, some gauges (usually lower pressure ranges such as
vacuum, up to 100 psi) may reflect a reading that is slightly “off zero”. To
properly “vent” the pressure gauge, please cut off tip of fill plug after you
have installed the instrument.
Operation &
Maintenance of Pressure Gauge
Storage
all
pressure gauges should be placed in dry storage under ambient room temperatures.
It is recommended to store the pressure gauges in their original packing boxes.
Inspection Frequency
Winters pressure gauges are rugged instruments featuring simplicity of design to
provide dependable and efficient service. The frequency of inspection is
dependent on the severity of service and how critical the accuracy of the
indicating pressure is. The inspection frequency can range from monthly to
annually basis.
Recalibration / Assembly & Disassembly Procedures
Remove the ring and lens
Slowly
pressurize the gauge to its full scale and slowly release the pressure back down
to zero Check the gauge at a minimum of four equal pressure intervals against a
Certified Test Gauge Adjust the movement accordingly by removing the pointer
with a pointer extractor. Be careful not to bend the pointer shaft Removing the
dial plate by loosening the holding screws When adjustments are complete,
replace the dial plate and pointer Re-check the gauge for accuracy Check lens
assembly gasket for any deformation, tears or cracks. If there are any visual
defects, the gasket will need to be replaced Re-assemble the lens assembly
Capsule-Type Pressure Gauge
The
same inspection procedure applies as per the positive pressure gauge section
above. The micrometer adjustable pointer is accessible by removing the white
plastic knob on the lens and adjusting the screw. This is done without having to
remove the lens. If calibration is required, please follow the outlined
procedure below. Remove lens by prying open the lens window with the notches
provided on the sides of the case Slowly pressurize the gauge to its full scale
and slowly release the pressure back down to zero Check the gauge at a minimum
of four equal pressure intervals against a Certified Test Gauge Adjust the
movement accordingly by removing the pointer with a pointer extractor. Be
careful not to bend the pointer shaft. Remove the dial plate by loosening the
holding screws when adjustments are complete, replace the dial plate and pointer
Re-check the gauge for accuracy Replace the lens window
For cleaning
Remove
the low pressure end cap with 1" (25.4 mm) spanner wrench; Remove the range
spring and the spacers at the bottom of the spring pocket. BE CAREFUL NOT TO
LOSE STACKING SPACERS, IF ANY, Remove the four ¼-20 socket head screws and
separate the body parts remove the diaphragm assembly to replace the diaphragm,
remove the screw at the top of the diaphragm disc to separate the assembly. DO
NOT REMOVE THE SCREW IN THE MAGNET ASSEMBLY Clean parts in a solvent solution
after removing the "O"-ring seals since solvents will attack the seal material
Place
diaphragm disc on magnet shaft with "O"-ring groove facing away from magnet.
Place new diaphragm over shaft with the open end of the convolution facing the
magnet. Place the second disc over diaphragm so that centre "O"-ring groove
faces diaphragm "O"-ring Replace the spring cup, and the #8-32 assembly screw.
Tighten to finish assembly Place the diaphragm assembly back into the diaphragm
pocket with the magnet end of the assembly at the high pressure side Reassemble
both body parts with the four ¼-20 socket head screw Insert the spacers and the
range spring into the spring pocket of the end cap. While holding the instrument
with the low pressure port down, insert the end cap back into the low pressure
side of the body Tighten the LO end cap and the instrument is now ready for
service No recalibration is required.
For replacing the lens
To
replace a broken lens, check to see if the lens is held on by a bezel or
snap-ring. To remove a bezel, which is a pressed on cover, either twist off by
hand or pry off with a screwdriver. To remove a snap-ring, pry out the ring with
a small screwdriver. Remove all glass chips, insert new lens and re-insert the
bezel or snap. With snap-rings, locate the ring joint at the bottom of the
gauge.
For replacing the pointer
Remove
bezel or snap-ring as previously described and clean out glass chips. Remove old
pointer with pointer extractor or two small screwdrivers opposite each other
under pointer hub. Pry off evenly being careful not to bend the pointer shaft.
Install new pointer on zero. NOTE: Gauges with a zero peg must have the pointer
set at a reference pressure (preferable mid-scale) to offset the preload against
the zero pegs. Re-install the lens, as described under lens replacement.
Gauge Mounting & Connection
Lower mount
(LM), center back mount (CBM), and/or lower back mount (LBM) are available for
most gauge types. Most of our standard gauges have NPT, or PT threaded
connections. Many gauges can be panel mounted using either a U-clamp bracket or
a front flange option. Pressure gauges should be mounted in the upright position
if possible.
