How to Read a P&ID - Pressure Control
This drawing demonstrates a pressure control loop for a hot water storage vessel (V-100). The pressure inside the vessel is regulated via a split-range pressure controller (PIC-101) which commands control valves to either introduce nitrogen gas for pressurization or vent excess gas to a vent line. The vessel is also equipped with temperature and level indication systems.
Source: images.png · Drawing: P&ID Drawings 101 - Corso Systems Training rev 17 · Components: 13 (2 equipment, 8 instrument, 3 valve)
Equipment (2)
| Tag | Description | Details | Connects to |
|---|---|---|---|
| V-100 | Hot Water Storage Tank | HOT WATER STORAGE | HEAT PAD, TT 102, LG 2, LT 100, V-1, V-2, PRV-1, PY 101A, PY 101B |
| HEAT PAD | Heat Pad | — | V-100, TIC 102 |
Instruments (8)
| Tag | Function (ISA 5.1) | Description | Details | Connects to |
|---|---|---|---|---|
| PY 101A | PY = Pressure Solenoid / Converter, Loop 101A | Nitrogen Control Valve and Actuator | — | V-100, PIC 101 |
| PY 101B | PY = Pressure Solenoid / Converter, Loop 101B | Vent Control Valve and Actuator | — | V-100, PIC 101 |
| PIC 101 | PIC = Pressure Indicating Controller, Loop 101 | Pressure Indicating Controller | — | PY 101A, PY 101B |
| 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 | Hot Water Inlet Globe Valve | Normally Closed (N.C.) | V-100 |
| V-2 | Outlet Globe Valve | Normally Closed (N.C.) | V-100 |
| PRV-1 | Pressure Relief Valve | Vents directly to atmosphere/vent line | V-100 |
Notes on drawing
- NITROGEN
- HOT WATER
- TO VENT
- TO USERS