Instrumentation Limited (IL) is a Government of India enterprise. The first unit of the company was established in Kota, Rajasthan in 1964 to manufacture "electronic and pneumatic instruments..." A second unit was established in 1974 in Palakkad, Kerela to manufacture "control valves, butterfly valves, pressure reducing valves, and allied equipment required by control and instrumentation packages..."

Activities: The Palakkad unit of Instrumentation Limited manufactures:

Pressure regulators used in the electro-pneumatic actuation systems of the Akash and Trishul surface-to-air missiles.

Sources:
[1] Instrumentation Limited, Palakkad, www.ilpgt.com;
[2] Dr. N.C. Birla and B.S. Murthy, eds., "Control and Guidance," Indian Defence Technology: Missile Systems (1998: DRDO, Ministry of Defence, New Delhi), pp. 137-138.