Scribd
Upload
661 views1 page

Pressure Range Selection: ASME B40.100-2005

The document discusses factors that influence pressure gauge range selection. It recommends that the operating pressure occur between 25-75% of the gauge's full scale. The full scale pressure should be around twice the operating pressure. It also notes that bourdon tube gauges are designed to operate in the middle third of the scale range for optimal readability. Operating at the low or high ends of the scale can impact accuracy, lifespan, and fatigue resistance. Proper range selection requires considering the normal operating pressure, system pressure limits, and priorities for readability, accuracy or durability.

Uploaded by

Shijumon Padavil
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
661 views1 page

Pressure Range Selection: ASME B40.100-2005

The document discusses factors that influence pressure gauge range selection. It recommends that the operating pressure occur between 25-75% of the gauge's full scale. The full scale pressure should be around twice the operating pressure. It also notes that bourdon tube gauges are designed to operate in the middle third of the scale range for optimal readability. Operating at the low or high ends of the scale can impact accuracy, lifespan, and fatigue resistance. Proper range selection requires considering the normal operating pressure, system pressure limits, and priorities for readability, accuracy or durability.

Uploaded by

Shijumon Padavil
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
You are on page 1/ 1

PRESSURE RANGE

SELECTION
There are several factors that influence pressure range selection. The following excerpt from ASME B40.100
explains along what portion of the scale the gauge should typically operate.

ASME B40.100-2005

4.3.1 Operating Pressure. The pressure gauge selected should


have a full-scale pressure such that the operating pressure occurs in
the middle half (25% to 75%) of the scale. The full-scale pressure of
the gauge selected should be approximately two times the intended
operating pressure.

Should it be necessary for the operating pressure to exceed 75%


of full scale, contact the supplier for recommendations.

This does not apply to test, retarded, or suppressed scale gauges.

Bourdon tube pressure gauges are designed and built to operate primarily in the middle third of the scale range so
that when the gauge is mounted in a vertical and upright position, the pointer will be as close as possible to the 12
o’clock position when reading pressure at normal operating conditions.

Although the gauge will operate full scale, there are other considerations to take into account. If the gauge is
primarily operating at the bottom of the scale (near zero), the accuracy or readability would be improved by using a
more appropriately applied lower range pressure gauge. (See ASME B40.1-2005) If, on the other hand, the gauge
is operating at the top of the scale (near the maximum pressure range of the gauge), the life span of the gauge may
be decreased, particularly if the gauge encounters high cycling, temperature extremes and/or excessive vibration.

• A bourdon tube is a curved and hardened or formed piece of metal designed to move a certain
amount based on the amount of force applied, then, return to its original shape when at rest, just
like a spring. As with any spring, the bourdon tube will fail after extended use. This failure could
be as simple as a loss of accuracy, failure to return to zero, or a release of the pressurized medium
into the case of the gauge or atmosphere. Note: Extended use could be time in service, number of
pressure cycles and extent of the pressure cycle. The larger the number of applied pressure cycles
and the greater the extent of the pressure cycle, the earlier the failure will occur.
• Bourdon tubes are by design highly stressed, especially in ranges over 1000 psi. Continuous
operation at full scale will result in early fatigue failure and subsequent rupture.
• Continuous, rapid pointer motion will result in excessive wear of the internal mechanism and cause
gross errors in accuracy, the pressure indicated and, also, possible early fatigue failure of the
bourdon tube. If the pointer motion is due to pressure pulsations, a suitable dampener should be
used between the pressure source and the gauge.

To choose the best range for your application, the following factors must be considered:
A. The normal operating pressure or average system pressure.
B. System pressure limits (both maximum and minimum).
C. Primary concern between readability, accuracy and/or durability.

See ASME B40.1 for additional details.

A Division of Engineered Specialty Products, Inc. General Information 175


10

You might also like