[File Name or Event] Emerson Confidential 27-Jun-01, Slide 1 Valve Automation PressureGuard Module...

[File Name or Event]Emerson Confidential27-Jun-01, Slide 1Valve Automation

PressureGuardPressureGuard

Module One - Introduction


Contents

SCH Actuator Design Philosophy

Key Features

Control System - Standard ComponentsStandard Control ComponentsComponents OverviewReservoirHandpumpHP GaugePressure RegulatorLP AccumulatorManual Reset Valve

Home


Contents

Control System - Shutdown ComponentsShutdown DevicesPressurematic PilotSP Pressure PilotPilot Accessories

Control System - OperationManual Operation / ArmingActuator Supply RegulationRemote ArmingRemote Shutdown

Home


SCH Actuator Design Philosophy

Self-Contained Hydraulic (SCH) actuators are most commonly used for applications in which automatic valve control is required but there is no external power source available to power the actuator.

The most common specific application is for ensuring valve shutdown on wellheads where an actuator power source is either unreliable or non existent.

The basic design philosophy for a SCH actuator is that a hydraulic handpump is used to pump hydraulic fluid under pressure into an actuator’s hydraulic cylinder which is used to compress the actuator’s spring as well as to move the mainline valve to its normal operating position.

In the event of a situation in which automatic valve operation is required, a control component is used to vent the hydraulic fluid from the actuator’s cylinder which allows the compressed spring to move the valve to its fail-safe position.

Home


Key Features

• Suitable for remote, unmanned, unpowered and critical service

• Adaptable to either quarter-turn or linear operated valves

• Field-proven in extreme climatic conditions

• Standard hydraulic model for all valve sizes and configurations

• Eliminates requirement for plant air, fuel gas, electricity or expensive nitrogen backup systems

• Modular design to simply maintenance

• High Pressure, zero leakage control

Home


Control System - Standard Components

All SCH actuator control systems are supplied with a basic manifolded control system which provides one-way local control via the handpump.

In addition to reliable and leak free mainline valve automation, the manifold based control system enables quick and simple maintenance.

Home


Control System - Components Overview

The standard SCH control system shown below is supplied as standard with the following control components:

Reservoir

HandpumpAssembly

HP Pressure GaugeHP ReliefValve

PressureRegulator

Actuator

Manual Reset Valve

LP Pressure Gauge

LP ReliefValve

LP Accumulator

Home


Contains hydraulic fluid for actuator and controls.

• Reservoir is non-pressurized (closed loop option available)• Houses both HP and LP relief valves• Fitted with hydraulic level indicator• Fitted with drain plug• Fitted with suction screen• Simple to remove for inspection and maintenance of internal components

Control Components - Reservoir

Home


Control Components - Handpump

Used to pressurize the hydraulic fluid, thereby compressing the actuator’s spring and moving the mainline valve to it’s normal operating position.

• Positive displacement• Weatherproof boot• Chrome plated ram• Replaceable discharge filter and check valve• Anodized aluminum handpump handle

Home


Monitors the hydraulic pressure in the high pressure line which also indicates the supply pressure available to the actuator.

• Stainless steel body• Liquid filled• Brass Bordon tube• Fitted with snubber

Control Components - HP Gauge

Home


Used to reduce to the hydraulic pressure in the high pressure actuator supply circuit (typically 1,000 to 1,200 psig) to a low pressure (typically 100 psig) allowing low pressure control components in the control circuit to be used downstream of the regulator.

• ENP brass body

Control Components - Pressure Regulator

Home


Monitors hydraulic pressure in the low pressure control circuit.

• Stainless steel body• Liquid filled• Brass Bordon tube• Fitted with snubber

Control Components - LP Gauge

Home


Prevents cyclic transfer, due to temperature changes, of hydraulic fluid from the high pressure actuator supply circuit to the low pressure control circuit and thereby prevents temperature induced creep of the actuator.

• Eliminates temperature induced actuator movement for -46°C to 77°C ambient temperature environments

Control Components - LP Accumulator

Home


Used to provide a local manual reset facility following mainline valve shutdown.

• High flow rates to provide fast mainline valve shutdown• Normally closed, manual reset, pilot operated relay

Control Components - Manual Reset Valve

Home


Control Components - Shutdown Devices

The standard SCH control system always requires at least one additional control component to initiate valve shutdown. This type of component is used to initiate the depressurization of the system allowing the spring in the actuator to move the mainline valve to its failed position.

Most common of these shutdown devices are pressure pilot valves, solenoid valves and manual ball valves.

The picture shows a Pressurematic Pilot fitted with a manual reset valve (P-MR type) being used as the shutdown device.

Manual Reset

PressurematicPilot

Home


Control Components - Pressurematic Pilot

All Pressurematic pilot valves provide high and low pipeline pressure sensing on gas or liquid pipelines and can be fitted with either an automatic or manual reset facility.

P-AR Pressurematic Pilot(Automatic Reset)

P-MR Pressurematic Pilot(Manual Reset)

Home


Control Components - SP Pressure Pilot

SP Pressure Pilot valves provide either high or low pipeline pressure sensing on gas or liquid pipelines and can be fitted with either an automatic or manual reset facility.

SP Pressure Pilot for sensing low (falling) pipeline pressure

SP Pressure Pilot for sensing high (rising) pipeline pressure

SP Pressure Pilot for sensing high (rising) pipeline pressure c/w manual reset valve

Home


Control Components - Pilot Accessories

In addition to pilot valves, Bettis Canada manufacture both ISO Test Valves and Flow Tees to assist with installation and calibration. Both components are available in a range of materials and trims to cover all types of pipeline media.

ISO Test Valve

Flow Tees

Home


1

Operation - Manual Operation / Arming

2

The Manual Reset Valve isarmed by pulling its toggle

to the manual position.

The HP Pressure Gauge measures the fluid pressure inthe HP Actuator Circuit and therefore the pressure being

supplied to the actuator from the handpump.

The HP Relief Valve limits the maximum pressure (typically 1200 psig)that can be generated by the handpump in the HP Actuator Circuit.

The LP Pressure Regulator limits the maximum pressure that is supplied(typically 100 psig) to the LP Control Circuit (shown in green).

The LP Accumulator prevents cyclic transfer, due to temperaturechanges, of hydraulic fluid from the high pressure actuator supply

circuit to the low pressure control circuit and thereby preventstemperature induced creep of the actuator.

The LP Pressure Gauge measures thefluid pressure in the LP Control Circuit.Raising the handpump handle sucks fluid from the

reservoir though an integral check valve. On thedown-stroke the fluid is forced under pressure

through a filter and another check valve into theHP Actuator Circuit (shown in red).

The LP Relief Valve prevents potential over-pressurization in theLP Control Circuit which could be caused by thermal fluid expansion.

During manual arming of the system, both the shutdown control component(shown here as a solenoid valve) and the Manual Reset Valve in the LP

Control Circuit are in the closed position; continued operation of the handpumpwill pressurize the circuit until the LP Pressure Regulator’s set-point is reached.

When the LP Control Circuit has been fully pressurized to theLP Pressure Regulator’s set-point no more fluid can pass

though the regulator. Continued handpump operation forcesmore fluid into the HP Actuator Circuit thereby increasing

the pressure in the circuit. The increasing pressurepressurizes the actuator’s hydraulic cylinder thereby

compressing its spring and stroking the mainline valve toits normal (here shown as open) operating position.

Home


Operation - Actuator Supply Regulation

Continued operation of the handpump after the actuatorhas stroked the mainline valve to its normal operating

position (shown here as open) will increase the pressurein the HP Actuator Circuit.

When the pressure in the HPActuator Circuit reaches the

set-point of the HP ReliefValve it will open, releasing fluidback to the Reservoir until the

pressure falls below its set-point. Continued operation

of the handpump will simplycause the HP Relief Valve tocontinue to vent fluid back to

the reservoir.

Home


Operation - Remote Arming

1

To initiate remote arming of the system, the ManualReset Valve has to be manually armed and thesystem pressurized via the handpump. After the

system has been pressurized, the shutdown device(here shown as a solenoid valve) has to be in the

open position (its normal operating position).Here the solenoid valve has been energized

to move it to the open position.

Once the shutdown device is in the open position,it allows a pilot signal to travel to the ManualReset Valve. When the Manual Reset Valve

senses the pilot signal, its spool moves slightlyallowing the toggle to move to the remotely

armed position. Once the Manual ResetValve is in the remotely armed position,loss of the pilot signal to it will result in

mainline valve shutdown.

Home


Operation - Remote Shutdown

During a failure condition, the shutdown control componentwill move to the closed position (here, the solenoid valve has

been de-energized). In the closed position, the shutdown deviceallows the fluid in the Manual Reset Valve pilot line to be vented

back to the reservoir, thereby depressurizing the line andallowing the Manual Reset Valve to move to the open position.

In the open position, the ManualReset Valve allows fluid fromthe LP Control Circuit to be

vented back to the reservoir.

As the LP Control Circuit begins to depressurize, the LPPressure Regulator senses the pressure drop and

attempts to maintain the pressure in the circuit by allowingfluid to pass though it from the HP Actuator Circuit. Duethe loss of fluid though the LP Pressure Regulator from

the HP Actuator Circuit, it begins to depressurize.

As the HP Actuator Circuit depressurizes and the pressurefrom the actuator’s hydraulic cylinder is removed, the springcauses the mainline valve to be stroked to its failed position

(here shown as closed).

Following the mainline valve shutdown, all fluid is returned backto the reservoir and both the HP Actuator and LP Control

circuits become fully depressurized.

Home


End of Module One

Home

Date post:	26-Mar-2015
Category:	Documents
Upload:	gabriel-reed
View:	214 times
Download:	1 times

[File Name or Event] Emerson Confidential 27-Jun-01, Slide 1 Valve Automation PressureGuard Module...

Documents