A–B–C–D–E–F–G–H–I–J–K–L–M–N–O–P–Q–R–S–T–U–V–W–X–Y
ID (Inside Diameter)
The measure of the inner diameter of a circular part.
IDS (Instrument Data Sheet)
A table summarizing data such as service, valve size, supply pressure, etc., necessary for actuator sizing.
In Situ (Maintenance)
To maintain or repair equipment “in its original place” such as a top-entry ball valve.
Incremental Seat Test
The leakage testing of valve seats in an assembled valve by increasing the applied pressure in prescribed pressure steps.
Inertia
The property of a body or mass of resisting to a change in velocity.
Injection Fitting
A fitting through which lubricant or sealant is injected.
Inlet Port
The port which is connected directly to the upstream side of a fluid system.
Inorganic Zinc Paint
Coating containing a zinc powder pigment in an inorganic vehicle.
Intelligent Pig (Smart Pig)
Intelligent pigs are inspection vehicles that move inside a pipeline pushed along by the flowing fluid. They are primarily used for the detection of wall thinning caused by ordinary corrosion.
Intensifier
A device which converts low pressure fluid power into a higher pressure.
Interlock
A mechanism which prevents the operation of a device until certain conditions have been satisfied. Normally electrical or mechanical safety devices.
Internal Pressure Relief
A self-relieving feature in non-independent seating valves that automatically relieves excessive internal body pressure caused by sudden changes in line pressures. By means of the piston effect principle, the excessive body pressure will move the seat away from its seating surface and relieve it to the lower pressure side.
Inverter
A device which converts DC voltage to AC voltage.
IP (Ingress Protection)
The degree of protection an enclosure provides against the entry of environmental contaminants.
IS (Intrinsically Safe) Circuit
A circuit in which any thermal effect or spark is not capable of causing ignition of flammable gas or material.
ISA
Instrument Society of America. www.isa.org
ISO (International Organization for Standardization)
It is a network of the national standards institutes of 157 countries. It is the world’s largest developer and publisher of International Standards. ISO’s work programme ranges from standards for activities such as agriculture, construction, engineering, manufacturing, logistics, information and communication technologies and services. www.iso.org
ISO 10497 (Firesafe Standard)
The ISO specification dealing with the fire testing of pipeline valves.