---
title: "How to Read a P&ID - Pressure Control — asset register"
doc_type: pid-asset-register
source: "images.png"
tags: [V-100, V-1, V-2, TT-102, TIC-102, PY-101A, PCV-101A, PIC-101, PY-101B-mid, PY-101B-top, PCV-101B, relief-valve-1, LG-2, LT-100, LI-100]
summary: "This diagram displays a pressure control scheme for a Hot Water Storage vessel (V-100). The pressure inside the vessel is regulated by a pressure indicator controller (PIC 101) which controls a nitrogen supply valve (PY 101A) and a vent valve (PY 101B). The system also features a temperature control loop using a heat pad and a level monitoring system."
---

# How to Read a P&ID - Pressure Control

This diagram displays a pressure control scheme for a Hot Water Storage vessel (V-100). The pressure inside the vessel is regulated by a pressure indicator controller (PIC 101) which controls a nitrogen supply valve (PY 101A) and a vent valve (PY 101B). The system also features a temperature control loop using a heat pad and a level monitoring system.

**Source:** images.png · **Components:** 15 (1 equipment, 9 instrument, 5 valve)

## Equipment (1)

| Tag | Description | Details | Connects to |
|---|---|---|---|
| V-100 | Hot Water Storage Tank | Service: HOT WATER STORAGE, includes HEAT PAD | V-1, V-2, TT-102, PCV-101A, PCV-101B, PY-101B-mid, relief-valve-1, LG-2, LT-100, TIC-102 |

## Instruments (9)

| Tag | Function (ISA 5.1) | Description | Details | Connects to |
|---|---|---|---|---|
| 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, V-100 |
| PY-101A | PY = Pressure Relay / Solenoid / Convertor, loop 101A | Pressure Transducer / Relay | — | PIC-101, PCV-101A |
| PIC-101 | PIC = Pressure Indicating Controller, loop 101 | Pressure Indicating Controller | — | PY-101A, PY-101B-top, PY-101B-mid |
| PY-101B-mid | PY = Pressure Relay / Solenoid / Convertor, loop 101B | Pressure Transducer / Relay | — | PIC-101, V-100 |
| PY-101B-top | PY = Pressure Relay / Solenoid / Convertor, loop 101B | Pressure Transducer / Relay | — | PIC-101, PCV-101B |
| 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 (5)

| Tag | Description | Details | Connects to |
|---|---|---|---|
| V-1 | Normally Closed Valve | N.C. (Normally Closed), Hot Water Line | V-100 |
| V-2 | Normally Closed Valve | N.C. (Normally Closed), Outlet to Users Line | V-100 |
| PCV-101A | Nitrogen Pressure Control Valve | — | PY-101A, V-100 |
| PCV-101B | Vent Pressure Control Valve | — | PY-101B-top, V-100 |
| relief-valve-1 | Pressure Relief Valve | Vents directly to atmosphere | V-100 |

## Notes on drawing

- P&ID Drawings 101 - Corso Systems Training
- Slide 17