{"dataset":"Valve Automation Accessories & Instrumentation Dataset","id":"valve-accessories","description":"Limit switch boxes, solenoid valves, positioners, gear operators and handwheel overrides: function, when required, compatible actuation and valve types, and governing standards.","publisher":"Vajra Industrial Solutions","publisherUrl":"https://www.vajravyuh.com","sourcePage":"https://www.vajravyuh.com/valve-accessories","downloadUrl":"https://www.vajravyuh.com/data/valve-accessories.json","license":"Free to use with attribution to Vajra Industrial Solutions (vajravyuh.com)","citation":"Vajra Valve Data Commons - Valve Accessories Dataset, Vajra Industrial Solutions, vajravyuh.com/data","disclaimer":"Engineering reference data for valve service; indicative only. Ratings and limits depend on concentration, temperature and service conditions. Verify against the governing standard and a qualified engineer before procurement.","recordDescription":"One record per accessory device class.","fields":["slug","name","category","function","howItWorks","whenRequired[]","actuationTypes[]","compatibleValveCategories[]","governingStandards[]","industries[]","considerations[]","productPage"],"recordCount":5,"records":[{"slug":"limit-switch-box","name":"Limit Switch Box","category":"position-feedback","function":"Sends a discrete open/closed position signal from an actuated valve back to the control room, DCS, PLC or ESD system, and gives local operators a visual position indication without inspecting the valve directly.","howItWorks":"Mounts on the actuator output via a NAMUR or direct-drive interface. A cam or magnet coupled to the actuator shaft trips mechanical micro-switches or proximity sensors as the valve reaches full open or full closed, sending a discrete signal (typically 24V DC or 230V AC) to the control system. Visual dome indicators give an instant local read of valve position.","whenRequired":["The valve's position must be visible in the control room or DCS/PLC without a field operator walking down to check","The valve is part of a Safety Instrumented System (SIS) and its closed-position feedback is part of the proof-test circuit","The installation is in a classified hazardous area, requiring Ex-rated switch and enclosure construction","Any actuated valve where remote confirmation of stroke completion is a plant requirement"],"actuationTypes":["pneumatic-actuator","electric-actuator"],"compatibleValveCategories":["ball-valves","butterfly-valves","plug-valves","gate-valves"],"governingStandards":["IEC 60529","ATEX","IECEx","IEC 61508","IEC 61511"],"industries":["oil-gas","chemical","power-generation","water-wastewater"],"considerations":["Ex d (flameproof) vs Ex ia (intrinsically safe) selection depends on the area classification and available power source","Mechanical cam switches are simpler and field-serviceable; proximity sensors have no moving parts but need a compatible signal isolator","Confirm the NAMUR or direct-mount interface matches the actuator top-works before ordering"],"productPage":"/products/accessories/limit-switch-box"},{"slug":"solenoid-valve","name":"Solenoid Valve","category":"actuator-control","function":"Acts as the electrically-operated pilot that commands a pneumatic actuator: it routes or vents instrument air to the actuator ports in response to a signal from the DCS, PLC or ESD system.","howItWorks":"An energised coil creates a magnetic field that shifts an internal plunger, directing compressed air to the actuator. De-energising the coil (including on power loss) returns the plunger by spring force, venting or redirecting air so the actuator drives to its fail-safe position. 3/2-way valves serve single-acting (spring-return) actuators; 5/2-way valves serve double-acting actuators; 5/3-way valves can lock the actuator in its last position on de-energisation.","whenRequired":["The valve must be operated remotely/automatically from a DCS, PLC or ESD system rather than manually","A defined fail-safe action (fail-open or fail-closed) is required on loss of electrical power","The application needs the actuator to lock in its last position rather than fail open or closed (5/3-way)"],"actuationTypes":["pneumatic-actuator"],"compatibleValveCategories":["ball-valves","butterfly-valves","plug-valves","control-valves"],"governingStandards":["NAMUR","ATEX","IECEx"],"industries":["oil-gas","chemical","lng-cryogenic","power-generation"],"considerations":["Coil voltage (24V DC, 110V AC, 220V AC) must match the plant's instrumentation power standard","Ex-proof coil and enclosure are mandatory in classified hazardous areas","Way configuration (3/2, 5/2, 5/3) is set by the actuator action, not by preference — confirm against the actuator's air port configuration before ordering"],"productPage":"/products/accessories/solenoid-valve"},{"slug":"valve-positioner","name":"Valve Positioner","category":"positioning-control","function":"Provides closed-loop control that drives a pneumatic actuator to the exact stem or disc position commanded by the control system, overcoming friction, backpressure and supply-air variation that would otherwise cause the valve to settle off-setpoint.","howItWorks":"Compares the actuator's actual stem position (via a feedback linkage or non-contact sensor) against the commanded signal (3-15 psi, 4-20 mA, HART, or fieldbus) and continuously trims the pneumatic output to the actuator until the error is eliminated. Digital/smart positioners add valve-signature diagnostics (friction and hysteresis trending) on top of the basic control function.","whenRequired":["The valve is in modulating/throttling service, not simple open-closed isolation","The valve's flow characteristic has an unstable region (e.g. a butterfly valve's 20-60 degree opening range) where small disc movements cause large flow swings","Digital diagnostics (valve signature, friction trending) or HART/fieldbus integration with the DCS is required"],"actuationTypes":["pneumatic-actuator"],"compatibleValveCategories":["control-valves","globe-valves","butterfly-valves"],"governingStandards":["NAMUR","IEC 60534","ATEX","IECEx"],"industries":["oil-gas","chemical","power-generation","pharmaceutical"],"considerations":["Pneumatic, electro-pneumatic and digital/smart positioners trade off cost against diagnostics — smart positioners justify themselves on predictive-maintenance value in critical loops","An unstable throttling range (common on butterfly valves) is a strong indicator that a positioner with a high-gain, anti-hunt filter is needed, not optional","Non-contact feedback sensors avoid the wear of mechanical linkages in high-cycle service"],"productPage":"/products/accessories/valve-positioner"},{"slug":"gear-operator","name":"Manual Gear Operator (Gearbox)","category":"manual-operation","function":"Gives a single operator the mechanical advantage to manually open or close large-bore or high-pressure valves that would otherwise need impractically high handwheel force.","howItWorks":"A worm or bevel gear train multiplies the operator's handwheel torque by the gear ratio (typically 10:1 to 100:1) while proportionally reducing output speed. Quarter-turn valves (ball, butterfly, plug) typically use a bevel or worm gear converting handwheel rotations into the 90-degree stroke; multi-turn gate and globe valves stack gear stages for very large or high-pressure rising-stem service.","whenRequired":["The valve is large-bore or high-pressure enough that direct handwheel operation would require impractical force","The valve is manually operated (no actuator) but still needs a practical, code-compliant means of operation","A declutchable interface is wanted so the valve can be automated with an actuator later without changing the valve top-works"],"actuationTypes":[],"compatibleValveCategories":["gate-valves","ball-valves","butterfly-valves","plug-valves"],"governingStandards":["ISO 5210","EN 15714-5","ISO 5211"],"industries":["oil-gas","water-wastewater","cement-mining","power-generation"],"considerations":["Higher gear ratios give more torque multiplication but require proportionally more handwheel turns to complete the stroke — a real operability tradeoff, not just a spec number","Bevel/worm gear for quarter-turn valves versus multi-stage gearing for multi-turn valves is set by the valve's stroke type, not by preference","Outdoor or buried service calls for weatherproof or Ex-proof gearbox construction"],"productPage":"/products/accessories/gear-operator"},{"slug":"handwheel-override","name":"Handwheel Override for Actuators","category":"manual-operation","function":"Lets an operator manually open or close an automated valve when instrument air or electrical power is unavailable, without removing the actuator.","howItWorks":"A declutchable gear train sits between the actuator output and the valve stem. In normal automatic operation the handwheel is disengaged and the actuator drives the valve directly. Engaging the clutch (pulling a knob or lever) locks the handwheel gear train to the actuator output shaft so turning the handwheel drives the valve manually. A spring-return-to-auto feature disengages the handwheel automatically once released, so automatic operation resumes without an operator having to remember to declutch it.","whenRequired":["The valve must remain operable manually during an instrument air or power outage","Commissioning or maintenance requires manual stroking of the valve before the actuator's control signal is available","An ESD or safety valve needs a defined manual-reset path after a trip"],"actuationTypes":["pneumatic-actuator","electric-actuator"],"compatibleValveCategories":["ball-valves","butterfly-valves","gate-valves","plug-valves"],"governingStandards":["ISO 5211","NAMUR"],"industries":["oil-gas","chemical","power-generation"],"considerations":["The spring-return-to-auto feature is a safety-critical detail — verify it before relying on the actuator to resume automatic control unattended","Mounting interface (NAMUR or ISO 5211) must match the actuator, the same as any other top-mounted accessory"],"productPage":"/products/accessories/handwheel-override"}]}