How to Read a P&ID - Pressure Control

This diagram illustrates pressure and temperature control loop concepts on a hot water storage tank (V-100) equipped with an external heat pad. A pressure indicating controller (PIC 101) manages the tank's internal pressure by split-ranging a nitrogen supply control valve and a vent control valve, while a temperature loop monitors and regulates the heating pad.

Source: images.png · Drawing: P&ID Drawings 101 · Components: 14 (2 equipment, 9 instrument, 3 valve)

Equipment (2)

Tag Description Details Connects to
V-100 Hot Water Storage Tank HOT WATER STORAGE V-1, V-2, LG 2, LT 100, TT 102, PY-101A, PY 101B (lower), relief-valve-1
HEAT PAD Heat Pad — TIC 102

Instruments (9)

Tag Function (ISA 5.1) Description Details Connects to
PY-101A PY = Pressure Solenoid/Converter, loop 101A Pressure Solenoid Valve — PIC 101, V-100
PIC 101 PIC = Pressure Indicating Controller, loop 101 Pressure Indicating Controller — PY-101A, PY 101B, PY 101B (lower)
PY 101B PY = Pressure Solenoid/Converter, loop 101B Pressure Solenoid Valve — PIC 101, V-100
PY 101B (lower) PY = Pressure Solenoid/Converter, loop 101B Pressure Relay — PIC 101, V-100
TT 102 TT = Temperature Transmitter, loop 102 Temperature Transmitter — V-100, TIC 102
TIC 102 TIC = Temperature Indicating Controller, loop 102 Temperature Indicating Controller — TT 102, HEAT PAD
LG 2 LG = Level Gauge, loop 2 Level Gauge — V-100
LT 100 LT = Level Transmitter, loop 100 Level Transmitter — V-100, LI 100
LI 100 LI = Level Indicator, loop 100 Level Indicator — LT 100

Valves (3)

Tag Description Details Connects to
V-1 Normally Closed Valve N.C. V-100
V-2 Normally Closed Valve N.C. V-100
relief-valve-1 Pressure Relief Valve Vents to atmosphere V-100

Notes on drawing