Pressure Standards Laboratory
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All pressure instruments used as standards in the National Weather Service (NWS) are calibrated in the Pressure Standards Laboratory (PSL) at Sterling, VA. The blue barometers to the left of the picture are the Paroscientific, Inc., model 760-16B (Paro-760) barometers and to the right are the white Coastal Environmental Systems, Precision Digital Barometers (PDB-1). The PSL’s Primary Standard, the Fluke Corporation piston gauge model PG7601-AMH, can be found in the center of the picture. |
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Background Information: |
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Per the National Weather Service (NWS) Directives (10-1302 and 10-1401), the Pressure Standards Lab (PSL) calibrates close to 500 barometers annually for the Observation Programs. To that effect, the PSL has two barometer recall programs, the Site-Owned Program and Exchange Program. The Site-Owned Program requires the Regional Field Sites to monitor the calibration cycle of the barometers on their property custodial area and return them to the PSL to be re-certified annually. The Site is responsible for sending the barometers to the PSL for calibration and may experience downtime while waiting for the barometers return for two to three days. Contrarily, the Exchange Program requires the PSL to monitor the calibration cycle of the barometers at Regional Sites and ship newly calibrated barometers to the Site in exchange for their current barometer. In this case, no downtime is experienced by the Site and the burden of monitoring the calibration cycle of the barometer is not the Site’s responsibility. The PSL supports these two programs with the following traveling standard barometers: (1) the Paroscientific, Inc. model 760-16B (Paro-760) barometer and the (2) the Coastal Environmental Systems model Precision Digital Barometer (PDB-1). The Paro-760 is part of the PSL’s Exchange and Site-Owned Programs for the Surface Observing Programs. The PDB-1 is part of the PSL’s Exchange Program for the Upper Air Observing Program. The Fluke piston gauge model PG7601-AMH is used as a primary standard for calibrating these barometers. Its performance characteristics along with those of other traveling standards used by the PSL can be found in the link below. |
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Automated Surface Observing System (ASOS) Exchange Program: |
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Each year, the PSL automatically replaces and recalls all ASOS Paro-760 traveling standard barometers in the field for calibration. Replacement barometers are sent with a recall reform. The completed form is sent back to the PSL to ensure that the next year replacement barometer is sent to the correct custodian (Note: replacement unit remains in PSL’s custodial area). If a barometer is shipped to another station or custodian by mistake, immediately notify the standards laboratory at nws.cal@noaa.gov or (703) 661-1230. Please return recalled barometers as soon as possible. |
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ASOS Site-Owned Barometer Program: |
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Site-owned Paro-760 standard barometers are not automatically recalled by the PSL. The Electronic Systems Analyst (ESA), Observing Program Leader (OPL), Data Acquisition Program Manager (DAPM), Meteorologist-in-Charge (MIC), or other custodian must return the instrument to the PSL once the one year calibration cycle of the unit is on the verge of elapsing. Care is taken by the PSL to ensure that these barometers are promptly re-certified and returned to the Site within two or three business days. |
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Voluntary Observing Ship (VOS) Barometer Exchange Program: |
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Each year, the standards laboratory automatically replaces and recalls all VOS Paro-760 traveling standard barometers for calibration. Replacement barometers are sent with a recall form. The completed form is sent back with the recalled barometer to ensure that the next year replacement barometer is sent to the correct Port Meteorological Officer (PMO) custodian (Note: unit remains on PSL’s custodial area). If a barometer is passed to another station or custodian by mistake, immediately notify the standards laboratory of the changed status at nws.cal@noaa.gov or (703) 661-1230. Return recalled VOS barometer as soon as possible. |
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Upper Air Observing Barometer Exchange Program: |
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Each year, the standards laboratory automatically replaces and recalls all Upper Air Program’s PDB-1 barometers for calibration. Replacement barometers are sent with a recall form. The completed form is sent back with the recalled barometer to ensure that the next year replacement barometer is sent to the correct custodian (Note: replacement unit remains in PSL’s custodial area).If an instrument is passed to another station or custodian by mistake, immediately notify the standards laboratory at nws.cal@noaa.gov or (703) 661-1230.Return recalled PDB-1 barometer as soon as possible as there are very few PDB-1 spares to support OCONUS and CONUS Upper Air Observations. |
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Field Maintenance of Paro-760 and PDB-1 Barometers: |
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The Paro-760 barometers require minimal field maintenance. The most important thing to remember is to keep the lead-acid battery in the barometer fully charged. Plug-in the AC cord with the switch off at every opportunity (overnight, weekend, going on leave, etc.). If the Paro-760 barometer goes into deep discharge, it may de-program (especially if the barometer is then exposed to a strong electro-magnetic field like a radiophone transmitter, etc.). Treat it like you would your own personal computer when using or shipping! If the instrument isn't working properly, you can't do your work properly. The PDB-1 is an even more versatile barometer than the Paro-760 barometer, but it cannot be moved from its assigned location because of programmed values put into the instrument. PDB-1 barometers have special boxes to protect the instrument. Keep it fully charged. It also has a lead-acid battery. Return barometer to the PSL in the provided shipping box when recalled for calibration. How to join the Exchange Program or donate Site-Owned Barometer: The PSL recommends all Site-Owned barometers be transferred to the Exchange Program. Once transferred, the site will maintain possession of the same amount of barometers supporting operations. The changes experienced by the Site after converting a barometer to PSL’s Exchange Program include the following: (1) Site receiving a different certified barometer every year to replace the recalled barometer; (2) the PSL taking on custodianship for barometer and responsibility for monitoring its calibration cycle; and (3) the elimination of downtime due to not having an operational barometer. To begin the transfer process of a barometer participating in the Site-Owned Program to the Exchange Program or to donate a Site-Owned barometer to the PSL, please fill out the Barometer Transfer Request form found under the “Forms” section below and submit to the PSL at nws.cal@noaa.gov. Contact Information: NOAA/NWS Pressure Standards Laboratory Forms: PSL Barometer Transfer Request Form (open with IE or Firefox) Related Links:
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