Pressure generator for portable instrument

• US 6,895,799 B2
• Filed: 12/15/2003
• Issued: 05/24/2005
• Est. Priority Date: 09/08/2001
• Status: Expired due to Term

• Current Assignee: Ashcroft Incorporated (Nagano Keiki Company Limited)
• Original Assignee: Dresser Incorporated (Nagano Keiki Company Limited)
• Inventors: Kosh, William Stephen
• Primary Examiner(s): RAEVIS, ROBERT R
• Application Number:
  US10/736,010
• Publication Number:
  US 20040123643A1
• Time in Patent Office: 526 Days
• Field of Search: 73 157- 159, 73 161- 169, 73/17.1, 73/17.2, 731/68
• US Class Current: 73/1.64
• CPC Class Codes: G01L 27/005 Apparatus for calibrating pressure sensors
• CPC Class Codes: Y10T 137/0379 By fluid pressure

Abstract

A compact, portable and NIST traceable pressure source dynamically generates very low pressures includes at least one adjustable valves in-line with a fluid, such as air, flowing through the valve. A differential pressure is created across a pressure control device downstream from the valve. The differential pressure varies depending on the volume of the gas flow and the amount of resistance to the gas flow. The pressure generating device utilizes a miniature pump to create a pressure, or, alternatively, a vacuum, that causes gas flow. The pressure generating device is compact and capable of providing a very low and stable differential pressure by using a dynamic flow that compensates for temperature changes and volume changes. The compact module may be configured as a plug-in module for existing handheld calibrators for operator ease of use.

Claims

1. A method for calibrating a pressure measuring instrument comprising the steps of:

dynamically generating a pressure differential with a pressure source disposed in a handheld device;

isolating the pressure source from communicating with a pressure sensor in the pressure measuring instrument;

adjusting at least one valve in the pressure source to achieve a desired pressure differential;

measuring the pressure differential with calibrated pressure sensor disposed in the handheld device;

allowing the pressure source to communicate with the sensor in the pressure measuring instrument;

comparing a pressure reading from the pressure measuring instrument to a pressure reading from the calibrated pressure sensor in the handheld device;

adjusting the pressure measuring instrument until the pressure reading from the pressure measuring instrument agrees with the pressure reading from the handheld device.

2. A method for calibrating a pressure measuring instrument comprising:

connecting a high pressure line and a low pressure line to the pressure measuring instrument;

isolating the high pressure line and the low pressure line from communicating with a pressure sensor in the pressure measuring instrument;

dynamically generating a pressure differential with a pressure generating module disposed in a handheld device connected to the high pressure line and the low pressure line of the measuring instrument;

adjusting at least one valve in the pressure generating module to achieve a desired pressure differential;

measuring the pressure differential with a calibrated pressure sensor disposed in the handheld device;

allowing the high pressure line and the low pressure line to communicate with the sensor in the pressure measuring instrument;

comparing a pressure reading from the pressure measuring instrument a pressure reading from the calibrated pressure sensor in the handheld device; and

adjusting the pressure measurement instrument until the pressure reading from the pressure measuring instrument agrees with the pressure reading from the handheld device.