Ashcroft 1495 User Manual
PRESSURE GAUGE
INSTALLATION,
OPERATION AND
MAINTENANCE
I&M008-10098-5/02 (250-1353H) 1M AMR 5P1/08
2
1.0 Selection and Application
1.1 Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
1.2 Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
1.3 Media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
1.4 Oxidizing media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
1.5 Pulsation/Vibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
1.6 Gauge fills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
1.7 Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
2.0 Temperature
2.1 Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
2.2 Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
2.3 Steam service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
2.4 Hot or very cold media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
2.5 Diaphragm seals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
2.6 Autoclaving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
3.0 Installation
3.1 Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
3.2 Gauge reuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
3.3 Tightening of gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
3.4 Process isolation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
3.5 Surface mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
3.6 Flush mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
CONTENTS
P
age
4.0 Operation
4.1 Frequency of inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
4.2 In-service inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
4.3 When to check accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
4.4 When to recalibrate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
4.5 Other considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
4.6 Spare parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
5.0 Gauge Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
6.0 Accuracy: Procedures/Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-10
6.1 Calibration - Rotary movement gauges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
6.2 Calibration - 1009 Duralife
®
Pressure Gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
6.3 Positive Pressure Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-15
3
CONTENTS
7.0 Diaphragm Seals
7.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
7.2 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
7.3 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
7.4 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
7.5 Failures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
8.0 Dampening Devices
8.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
8.2 Throttle Screws & Plugs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
8.3 Ashcroft Gauge Saver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
8.4 Ashcroft Pulsation Dampener . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
8.5 Ashcroft Pressure Snubber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
8.6 Campbell Micro-Bean
8.7 Ashcroft Needle Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
8.8 Chemiquip
®
9.0 Resources
9.1 Training Videos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
9.2 Pressure Instrument Testing Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
9.3 Tools & Tool Kits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Page
®
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Pressure Limiting Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Cover photo courtesy of Johnson/Yokogawa Co.
Campbell Micro-Bean®is a registered trademark of J.A. Campbell Co.
Chemiquip®is a registered trademark of Chemiquip Products Co. Inc.
4
1.0 SELECTION & APPLICATION
Users should become familiar with ASME
B40.1 (Gauges – Pressure Indicating Dial
Type – Elastic Element) before specifying
pressure measuring instruments. That document – containing valuable information
regarding gauge construction, accuracy, safety,
selection and testing – may be ordered from:
ASME International
Three Park Avenue
New York, N.Y. 10016-5990
800-843-2763 (US/Canada)
95-800-843-2763 (Mexico)
973-882-1167 outside North America
Email: infocentral@asme.org
WARNING:
sure gauges should be selected considering
media and ambient operating conditions.
Improper application can be detrimental to the
gauge, causing failure and possible personal
injury, property damage or death. The information contained in this manual is offered as
a guide in making the proper selection of a
pressure gauge. Additional information is
available from Ashcroft Inc.
The following is a highlight of some of the more
important considerations:
1.1 Range – The range of the instrument
should be approximately twice the maximum
operating pressure. Too low a range may
result in (a) low fatigue life of the elastic element due to high operating stress and (b) susceptibility to overpressure set due to pressure
transients that exceed the normal operating
pressure. Too high a range may yield insufficient resolution for the application.
1.2 Temperature – Refer to page 6 of this
manual for important information concerning
temperature related limitations of pressure
gauges, both dry and liquid filled.
1.3 Media – The material of the process sensing
element must be compatible with the process
media. Use of a dia-phragm seal with the gauge
is recommended for process media that (a) are
corrosive to the process sensing element; (b)
To prevent misapplication, pres-
ontain heavy particulates (slurries) or (c) are
c
very viscous including those that harden at
room temperature.
1.4 Oxidizing media – Gauges for direct use
on oxidizing media should be specially
cleaned. Gauges for oxygen service should be
ordered to variation X6B and will carry the
ASME required dial marking “USE NO OIL”
in red letters. Gauges for direct use on other
oxidizing media may be ordered to variation
X6W. They will be cleaned but carry no dial
marking. Plus!
®
gauges or Halocarbon filled
gauge or diaphragm fill is required for use
with oxidizing media; order variation XCF.
1.5 Pulsation/Vibration – Pressure pulsation
can be dampened by several mechanisms; the
patented PLUS! Performance gauge will han-
dle the vast majority of applications. One
exception to this is high frequency pulsation
which is difficult to detect. The only indication
may be an upscale zero shift due to movement
wear. These applications should be addressed
with a liquid filled gauge, or in extreme cases,
a remotely mounted liquid filled gauge connected with a length of capillary line. The
small diameter of the capillary provides excellent dampening, but can be plugged. The
Ashcroft 1106 pulsation dampener and 112
snubber are auxiliary devices which dampen
pulsation with less tendency to plug.
1.6 Gauge fills. – Once it has been determined
that a liquid filled gauge is in order, the next
step is selecting the type of fill. Glycerin satisfies most applications. While being the least
expensive fill, its usable temperature range is
20/250°F. Silicone filled gauges have a
broader service range: –40/250°F. Oxidizing
media require the use of Halocarbon, with a
service range of –50/250°F. Pointer motion
will be slowed at the low end of the low end of
these temperature ranges.
1.7 Mounting – Users should predetermine
how the gauge will be mounted in service:
stem (pipe), wall (surface) or panel (flush).
Ashcroft wall or panel mounting kits should be
ordered with
the gauge. See paragraph 3
Installation.
5
2.0 TEMPERATURE
2.1 Ambient Temperature – To ensure long
life and accuracy, pressure gauges should
preferably be used at an ambient temperature between –20 and +150F (–30 to +65C). At
very low temperatures, standard gauges may
exhibit slow pointer response. Above 150F, the
accuracy will be affected by approximately
1.5% per 100F. Other than discoloration of the
dial and hardening of the gasketing, non-liquid filled type 1279 (phenolic case) and 1379
(aluminum case) Duragauge
glass windows, and Duralife
1008 and 1009, can withstand continuous
operating temperatures up to 250F. Liquid
filled gauges can withstand 200F but glycerin
fill and the acrylic window of Duragauge
gauges will tend to yellow. Silicone fill will
have much less tendency to yellow. Low pressure, liquid filled types 1008 and 1009 gauges
may have some downscale errors caused by
liquid fill expansion. This can be alleviated by
“burping” the gauge by gently pushing the top
fill plug to one side to admit air to the case.
Although the gauge may be destroyed and calibration lost, gauges can withstand short
times at the following temperatures: gauges
with all welded pressure boundary joints,
750F (400C); gauges with silver brazed joints,
450F (232C) and gauges with soft soldered
joints, 250F (121C). For expected long term
service below –20F (–30C) Duragauge
1
⁄
2˝ 1009 gauges should be hermetically
4
sealed and specially lubricated; add “H” to the
product code for hermetic sealing. Add variation XVY for special lubricant. Standard
Duralife gauges may be used to –50F (–45C)
without modification.
2.2 Accuracy – Heat and cold affect accuracy
of indication. A general rule of thumb for dry
gauges is 0.5% of full scale change for every
40°F change from 75°F. Double that allowance
for gauges with hermetically sealed or liquid
filled cases, except for Duragauge
where no extra allowance is required due to
the elastomeric, compensating back. Above
250°F there may exist very significant errors
in indication.
®
, with standard
®
gauges types
®
and
®
gauges
.3 Steam service – In order to prevent live
2
steam from entering the Bourdon tube, a
siphon filled with water
should be installed
between the gauge and the process line.
Siphons can be supplied with ratings up to
4,000 psi. If freezing of the condensate in the
loop of the siphon is a possibility, a diaphragm
seal should be used to isolate the gauge from
the process steam. Siphons should also be
used whenever condensing, hot vapors (not
just steam) are present. Super heated steam
should have enough piping or capillary line
ahead of the siphon to maintain liquid water
in the siphon loop.
2.4 Hot or very cold media – A five foot capillary line assembly will bring most hot or cold
®
process media within the recommended gauge
ambient temperature range. For media above
750F (400C) the customer should use his own
small diameter piping to avoid possible corrosion of the stainless steel.The five foot capillary
will protect the gauges used on the common
cryogenic (less than –300F (200C) gases, liquid
argon, nitrogen, and oxygen. The capillary and
gauge must be cleaned for oxygen service. The
media must not be corrosive to stainless steel,
and must not plug the small bore ofthe capillary.
2.5 Diaphragm seals – As mentioned above, a
diaphragm seal should be used to protect
gauges from corrosive media, or media that
will plug the instrument. Diaphragm seals
are offered in a wide variety of designs and
corrosion resistant materials to accommodate
almost any application and most connections.
Request bulletin OH-1 for details.
2.6 Autoclaving – Sanitary gauges with
clamp type connections are frequently steam
sterilized in an autoclave. Gauges equipped
with polysulfone windows will withstand
more autoclave cycles than those equipped
with polycarbonate windows. Gauges
equipped with plain glass or laminated safety
glass should not be autoclaved. Gauge
cases should be vented to atmosphere (removing the rubber fill/safety plug if necessary)
before autoclaving to prevent the plastic
window from cracking or excessively distorting. If the gauge is liquid filled, the fill should
6
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