Intelligent pressure probe

• US 5,325,312 A
• Filed: 03/12/1993
• Issued: 06/28/1994
• Est. Priority Date: 03/12/1993
• Status: Expired due to Fees

• Current Assignee: Emerson Electric Company
• Original Assignee: Emerson Electric Company
• Inventors: Kidd, Roy E.
• Primary Examiner(s): Teska, Kevin J.
• Application Number:
  US08/030,982
• Time in Patent Office: 473 Days
• Field of Search: 364/558, 364/465, 364/556, 73/4 R, 73/37, 73/40, 340/605, 340/626
• US Class Current: 702/51
• CPC Class Codes: G01M 3/2892 for underground fuel dispensing systems G01M3/30 takes precedence

Abstract

A pressure transducer, a microprocessor, and associated electronics are enclosed in a probe housing which may be attached to a liquid product line with the pressure transducer responsive to the pressure of the liquid in the liquid product line to provide an electrical signal representative of the pressure. The probe microprocessor contains a software program to detect leakage from a pressurized liquid product line in which the liquid is subject to a pressure increase caused by thermal contraction. The probe also has the capability to directly operate a product pump with a signal connection between the probe and the pump.

Claims

1. A line pressure probe for use in a liquid storage and dispensing system, the line pressure probe comprising:

(a) a pressure transducer for providing an electrical signal representative of the pressure in a liquid conduit;

(b) digital storage means for storing a plurality of decision criteria related to conditions of said liquid storage and dispensing system and the pressure in the conduit;

(c) digital logic means responsive to the pressure signal and communicating with the digital storage means for providing an output signal indicative of one or more conditions of said liquid storage and dispensing system relative to the pressure signal;

(d) probe housing for enclosing the pressure transducer, digital storage means and digital logic means including means for attaching the probe housing to a liquid conduit with the pressure transducer responsive to the pressure of the liquid in the conduit; and

, a signal path for exclusively connecting the digital logic means to a pump relay, so the digital logic means directly activates a pump to pressurize the liquid conduit.

2. The line pressure probe as recited in claim 1 wherein the digital logic means directly activates a pump to repressurize the liquid conduit to compensate for thermal contraction.

3. The line pressure probe as recited in claim 2 wherein when the liquid conduit is repressurized and the line pressure probe performs a line tightness test.

4. The line pressure probe as recited in claim 3 wherein the probe determines whether to repressurize the liquid conduit upon completion of a line tightness test by:

(a) determining if the pump is "on" or "off", if the pump is "on", reset line tightness test variable because product is being dispensed and upon completion of product being dispensed restarting the line tightness test sequence; and

,

(b) operating the pump for a period to repressurize the liquid conduit and if after the period is over the pump it "off" restart the line tightness test sequence.