# US 9,752,599 B2 · Methods and apparatus to partial stroke test valves using pressure control > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,752,599 B2 - Document ID: US9752599B2 - Status: Granted - Kind: B2 - Application number: 14/272,090 - Filed: 2014-05-07 - Published: 2015-11-12 - Granted: 2017-09-05 - Earliest claimed: 2014-05-07 - Assignees: Fisher Controls International LLC - Applicants: Fisher Controls International LLC - Inventors: Kenneth William Junk - Web page: https://patentgrep.com/patent/US9752599B2 ## CPC - F15B 19/005: {Fault detection or monitoring} - F15B 19/00: Testing; {Calibrating; Fault detection or monitoring; Simulation or modelling of} fluid-pressure systems or apparatus not otherwise provided for - F15B 19/002: {Calibrating} - F16K 37/0025: {Electrical or magnetic means (F16K37/0075 takes precedence)} - F16K 37/005: {for measuring fluid parameters (F16K37/0033 takes precedence)} - F16K 37/0075: {For recording or indicating the functioning of a valve in combination with test equipment} - F16K 37/0091: {by measuring fluid parameters} - G05B 15/02: electric - G05D 7/06: characterised by the use of electric means {(G05D7/005 takes precedence)} - G05D 7/0635: {by action on throttling means (G05D7/0688, G05D7/0694 take precedence)} - F15B 5/006: {with electrical means, e.g. electropneumatic transducer (F15B5/003 takes precedence)} - F15B 2211/864: Failure of an output member, e.g. actuator or motor failure - F15B 2211/87: Detection of failures - F15B: SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR - F16K: VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING {(devices for emptying and evacuating the excess liquid in valves or conduits F16L55/07)} - G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G) - G05D: SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES ## Abstract Methods and apparatus to partial stroke test valves using pressure control are disclosed. An example method includes generating a first pressure set point for a valve positioner coupled to an actuator to actuate a valve. The first pressure set point is associated with a partial stroke test of the valve. The example method also includes controlling an output pressure of the positioner towards the first pressure set point to actuate the valve in a stroke direction. The example method further includes determining whether the valve is stuck based on the output pressure. ## Claims ### Claim 1 A method comprising: generating a first pressure set point for a valve positioner coupled to an actuator to actuate a first valve, the valve positioner including a fluidly-actuated second valve; controlling, with the fluidly-actuated second valve, an output pressure of the positioner towards the first pressure set point to actuate the first valve in a stroke direction; defining a target travel position associated with a partial stroke test of the first valve; measuring a position of the first valve; generating a second pressure set point after the position of the first valve reaches the target travel position to actuate the first valve in a return direction towards an initial position of the first valve associated with the position of the first valve before the partial stroke test; controlling, with the fluidly-actuated second valve, the output pressure of the positioner towards the second pressure set point; defining a pressure threshold associated with the second pressure set point; defining a threshold displacement of the first valve from the initial position; and determining that the first valve is stuck while controlling the first valve in the return direction if the output pressure passes the pressure threshold associated with the second pressure set point while the position of the first valve is outside the threshold displacement from the initial position. ### Claim 2 (depends on 1) The method of claim 1, further comprising: converting, with a current-to-pressure transducer of the valve positioner in fluid communication with the fluidly-actuated second valve, an electrical signal based on the first pressure set point and a bias to a pressure signal; and controlling, with the fluidly-actuated second valve, the output pressure of the positioner towards the first pressure set point based on the pressure signal. ### Claim 3 (depends on 1) The method of claim 1, further comprising ramping the first pressure set point over time to actuate the first valve as the output pressure is controlled towards the first pressure set point. ### Claim 4 (depends on 1) The method of claim 1, further comprising: defining a pressure threshold associated with the first pressure set point; and determining that the first valve is stuck while controlling the first valve in the stroke direction if the output pressure passes the pressure threshold associated with the first pressure set point before the position of the first valve reaches the target travel position. ### Claim 5 (depends on 4) The method of claim 4, further comprising: determining an initial output pressure associated with the positioner before the partial stroke test; and controlling, with the fluidly-actuated second valve, the output pressure of the positioner back to the initial output pressure after determining the first valve is stuck while controlling the first valve in the stroke direction. ### Claim 6 (depends on 1) The method of claim 1, wherein the first valve is a safety shutoff valve. ### Claim 7 (depends on 1) The method of claim 1, wherein the first valve is an on-off valve. ### Claim 8 (depends on 1) The method of claim 1, wherein friction in the first valve creates stick-slip dynamics when the first valve is actuated. ### Claim 9 A valve positioner comprising: a travel controller to: define a target travel position for a first valve coupled to the valve positioner via an actuator; and monitor a position of the first valve; a pressure controller including a fluidly-actuated second valve to: control, during a partial stroke test, an output pressure of the positioner towards a first pressure set point to actuate the first valve towards the target travel position as the output pressure is controlled towards the first pressure set point; and control, during the partial stroke test, the output pressure of the positioner towards a second pressure set point after the position of the first valve reaches the target travel position, the second pressure set point to actuate the first valve towards an initial position of the first valve associated with the position of the first valve before the partial stroke test; and a limiter to define a pressure threshold associated with the second pressure set point and to define a threshold displacement of the first valve from the initial position, the pressure controller to generate an alert indicating that the first valve is stuck if the output pressure passes the pressure threshold associated with the second pressure set point while the position of the first valve is outside the threshold displacement from the initial position. ### Claim 10 (depends on 9) The valve positioner of claim 9, wherein: the pressure controller includes a current-to-pressure transducer in fluid communication with the fluidly-actuated second valve, the current-to-pressure transducer to convert an electrical signal based on the first pressure set point and a bias to a pressure signal, the fluidly-actuated second valve to control the output pressure of the positioner towards the first pressure set point based on the pressure signal. ### Claim 11 (depends on 9) The valve positioner of claim 9, wherein the limiter is to define a pressure threshold associated with the first pressure set point, the pressure controller to generate an alert indicating that the first valve is stuck if the output pressure passes the pressure threshold associated with the first pressure set point before the position of the first valve reaches the target travel position. ### Claim 12 A tangible computer readable storage medium comprising instructions that, when executed, cause a machine to at least: generate a first pressure set point for a valve positioner coupled to an actuator to actuate a first valve, the valve positioner including a fluidly-actuated second valve; control, with the fluidly-actuated second valve, an output pressure of the positioner towards the first pressure set point to actuate the first valve in a stroke direction; define a target travel position associated with a partial stroke test of the first valve; measure a position of the first valve; generate a second pressure set point after the position of the first valve reaches the target travel position to actuate the first valve in a return direction towards an initial position of the first valve associated with the position of the first valve before the partial stroke test; control, with the fluidly-actuated second valve, the output pressure of the positioner towards the second pressure set point; define a pressure threshold associated with the second pressure set point; define a threshold displacement of the first valve from the initial position; and determine that the first valve is stuck while controlling the first valve in the return direction if the output pressure passes the pressure threshold associated with the second pressure set point while the position of the first valve is outside the threshold displacement from the initial position. ### Claim 13 (depends on 12) The computer readable storage medium of claim 12, wherein the instructions further cause the machine to: convert, with a current-to-pressure transducer of the valve positioner in fluid communication with the fluidly-actuated second valve, an electrical signal based on the first pressure set point and a bias to a pressure signal; and control, with the fluidly-actuated second valve, the output pressure of the positioner towards the first pressure set point based on the pressure signal. ### Claim 14 (depends on 12) The computer readable storage medium of claim 12, wherein the instructions further cause the machine to ramp the first pressure set point over time to actuate the first valve as the output pressure is controlled towards the first pressure set point. ### Claim 15 (depends on 12) The computer readable storage medium of claim 12, wherein the instructions further cause the machine to: define a pressure threshold associated with the first pressure set point; and determine that the first valve is stuck while controlling the first valve in the stroke direction if the output pressure passes the pressure threshold associated with the first pressure set point before the position of the first valve reaches the target travel position. ### Claim 16 (depends on 15) The computer readable storage medium of claim 15, wherein the instructions further cause the machine to: determine an initial output pressure associated with the positioner before the partial stroke test; and control, with the fluidly-actuated second valve, the output pressure of the positioner back to the initial output pressure after determining the first valve is stuck while controlling the first valve in the stroke direction.