Portable electro-pneumatic calibrator

• US 4,569,221 A
• Filed: 10/24/1983
• Issued: 02/11/1986
• Est. Priority Date: 10/24/1983
• Status: Expired due to Fees

• Current Assignee: August M. Snook Jr
• Original Assignee: August M. Snook Jr
• Inventors: Snook, August M. Jr.
• Primary Examiner(s): Swisher, S. Clement
• Application Number:
  US06/544,620
• Time in Patent Office: 841 Days
• Field of Search: 73/4 R
• US Class Current: 73/1.61
• CPC Class Codes: G01F 25/10 of flowmeters

Abstract

An electro-pneumatic calibrator to be used in testing and calibration of electro-pneumatic devices having the capability of generating or measuring air pressure in psi, current in milliamps or voltage and measuring air pressure in inches of water or resistance in ohms. A plurality of separate digital meters allow simultaneous use of the separate functions. The apparatus includes a switch and two potentiometers which allows setting variable zero points and spans when the apparatus is used to generate a current or voltage and quickly switching between the set zero point and span.

Claims

1. A multifunction portable calibration unit for testing electrical or pneumatic meters or gauges comprising in combination:

a housing having a plurality of display devices mounted thereon exteriorally readable by an operator of said calibration unit;

a first pneumatic means for supplying a regulated air pressure from an air pressure source or receiving an unknown pressure, for measuring the regulated pressure or unknown pressure, and for displaying the pressure measurement on a first display device;

a second pneumatic means for supplying a regulated air pressure from said air pressure source, for measuring the regulated pressure, and for displaying the pressure measurement on a second display device and further including means to vent the regulated air pressure in order to supply a known pressure or atmospheric pressure alternately; and

an electrical means for supplying a regulated current or voltage or receiving an unknown current or voltage and displaying the measured current or voltage on a third display device;

said first pneumatic means, said second pneumatic means and said electrical means being housed in said housing and having a common power source.

2. The multifunction portable calibration unit of claim 1 wherein said power source comprises a battery to supply power for said display means and said third electrical means.

3. The calibration unit of claim 2 further including battery test means for determining the condition of said battery.

4. The power source of claim 2, further including jacks to receive power from an external power source and an isolating circuit to prevent damages to said battery when said external power source is used.

5. The calibration unit of claim 1 wherein said first pneumatic means comprises in series:

an inlet port for receiving air pressure from a pressure source;

a precision pressure regulator to control the pressure from said inlet port;

an on-off valve; and

pressure display means in parallel with a pressure input/output port.

6. The pneumatic means of claim 5 wherein said display means comprises:

a precision pressure transducer to convert air pressure into an electrical signal; and

a digital meter calibrated to receive said electrical signal and to display a digital readout of the measured pressure in pounds per square inch.

7. The display means of claim 6 wherein said meter further includes an on-off switch for said digital meter between said meter and the meter power source.

8. The multifunction calibration unit of claim 1 wherein said second pneumatic means comprises:

an inlet port for receiving air pressure from a pressure source;

a precision pressure regulator to control the pressure from said inlet port; and

in parallel, a pressure display means and a valve to vent the regulated air pressure or direct the regulated air pressure to an outlet port.

9. The second pneumatic means of claim 8 wherein said display means comprises:

a precision pressure transducer for converting air pressure into an electrical signal; and

a digital meter calibrated to receive said electrical signal and display a digital readout of the measured pressure in inches of water.

10. The display means of claim 9 wherein said meter further includes an on-off switch for said digital meter between said meter and the meter power source.

11. The multifunction calibration unit of claim 1 wherein said electrical means comprises:

input/output means for receiving electrical leads to be connected to a device to be tested;

a display means to display the current or voltage measured at the input/output means;

a power supply which may be selectively connected to said input/output means; and

switch means interconnecting said input/output means, said display means and said power supply to allow said input/output means to act as a source of current or voltage or to measure currents or voltage.

12. The electrical means of claim 11 wherein said switch means comprises a four pole six position switch, wherein:

a first position comprises a circuit to supply a current including said display means, said power source, said input/output means, a resistor, and means to adjust a zero point and a span of said current in order to alternately supply a known zero or span current to said input/output means;

a second position comprises a circuit to measure current including said input/output means, said display means and a resistor to measure the current flowing to the input/output means;

a third position comprising a circuit to measure voltage including said input/output means, and said display means in order to measure the voltage across said input/output means;

a fourth position comprising a circuit to supply a variable current including said input/output means, said power source, a resistor, and said display means in order to provide a variable current at said input/output means;

a fifth position comprising a circuit to supply a voltage including said input/output means, said power source, a resistor, said display means and means to adjust a zero point and a span of said voltage in order to alternately supply a known zero or span voltage in order to supply a variable voltage at said input/output means; and

a sixth position comprising a circuit including said input/output means, said power source, and said display means to allow said input/output means to measure resistance.

13. The electrical means of claim 11 wherein said input/output means comprises jacks for receiving plugs on electrical leads.

14. The electrical means of claim 11 wherein said display means comprises a digital meter calibrated to receive an electrical signal and display the value of the signal being supplied in volts, amps or ohms.

15. The display means of claim 14 wherein said meter further includes an on-off switch for said digital meter between said meter and the meter power source.