Fluke Calibration P3XXX Deadweight Tester, 2400, PG7000 Piston Gauge Application Note

Accounting for gravity
when using a deadweight
tester or piston gauge
Application Note
To establish pressures using
a deadweight tester (DWT) or
piston gauge, the user must
account for the acceleration of
gravity at the location where
the instrument is operated. It
is important to note that the
acceleration of gravity varies
substantially around the world.
With a range of approximately
0.5 %, the local gravity correction is typically the largest
environmental influence acting
on the deadweight tester.
The most accurate method for the user to determine the acceleration of gravity at the laboratory
or other site where the deadweight tester will be
used is to have a site survey performed. There are
various companies that can provide this type of
service. Although this is the most accurate method,
it can also be expensive.
To determine the acceleration of local gravity value when a survey or site measurement is
unavailable, the resources listed below are available on the Internet.
1. Use one of the following options to determine
the latitude, longitude, and elevation at the site
the deadweight tester will be used:
• Obtain latitude and longitude coordinates
using a GPS receiver, or
• Use an Internet-based geo-coding program
–http://maps.google.com (use “link” button to
show Lat-Lon)
–http://www.getlatlon.com
–http://mapper.acme.com
–http://itouchmap.com/latlong.html
2. Enter latitude and longitude coordinates into one
of the following internet-based programs:
• NOAA/NGS web site (limited to the
contiguous 48 United States)
–http://www.ngs.noaa.gov/cgi-bin/
grav_pdx.prl
• PTB (National Metrology Laboratory of
Germany) web site (global)
–http://www.ptb.de/cartoweb3/
SISproject.php
F ro m t h e F l u k e C a l i b r a t i o n D i g i t a l L i b r a r y @ w w w. f l u k e c a l . c o m / l i b r a r y
For the P3XXX Series Deadweight Testers,
customers have two choices. The deadweight
tester can be provided matched to standard gravity (9.80665 m/s2) and the customer can utilize
software (such as Fluke Calibration PressCal) to
account for the acceleration of local gravity. Or, the
deadweight tester can be provided matched to the
local gravity value supplied by the customer. This
is a service Fluke Calibration offers at no additional
charge. In the latter case, customers must provide
their local gravity on the purchase order.
For piston gauges, such as the 2400 Series
and PG7000 Series, the local gravity must be
entered into either the terminal (PG7000 series)
or software that will be used for the piston gauge
calculation (WinPrompt or COMPASS® for Pressure
software).
For customers who do not have a site survey,
the methods available on the Internet provide a
possible resource for determining the gravity at
their location. The uncertainties estimated using
this method range from about 0.0002 % up to
0.002 %. Customers should use these at their own
discretion to determine if the local gravity provided
is suitable for the intended use.
Fluke Calibration. Precision, performance, confidence.™
Fluke Calibration
PO Box 9090,
Everett, WA 98206 U.S.A.
Fluke Europe B.V.
PO Box 1186, 5602 BD
Eindhoven, The Netherlands
For more information call:
In the U.S.A. (877) 355-3225 or Fax (425) 446-5116
In Europe/M-East/Africa +31 (0) 40 2675 200 or Fax +31 (0) 40 2675 222
In Canada (800)-36-FLUKE or Fax (905) 890-6866
From other countries +1 (425) 446-5500 or Fax +1 (425) 446-5116
Web access: http://www.flukecal.com
©2012 Fluke Calibration. Specifications subject to change without notice.
Printed in U.S.A. 5/2012 4218960A_EN
Pub_ID: xxxxx-eng
Modification of this document is not permitted without written permission
from Fluke Calibration.
2 Fluke Calibration Accounting for gravity when using a deadweight tester or piston gauge