---
title: "Short note: Sluice valve"
subject: "Water Supply Engineering"
chapter: 9
key: "semester_5/water_supply_engineering:sluice-valve-note"
source: https://www.bctengineer.com/q/semester_5/water_supply_engineering/sluice-valve-note
site: BCT Engineering
---

# Short note: Sluice valve

Water Supply Engineering · Chapter 9: Valves and Fittings

- Asked in: 2081 Bhadra, 5 marks
- Video: [Environment lecture ! types of  Valve in pipe ! Sluice valve ! Reflux valve ! Air relief valve !](https://www.youtube.com/watch?v=Vei7FUX9Ze8) — NARAYANA COACHING CLASSES
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/water_supply_engineering/sluice-valve-note
- Whole chapter: https://www.bctengineer.com/md/semester_5/water_supply_engineering/chapter-9

## Question

Write a short note on the sluice valve with sketch.

## Short answer

A sluice (gate) valve opens or closes flow completely by moving a wedge gate across the pipe with a screw spindle. It offers low head loss when fully open, tight shut-off, but is unsuitable for throttling and is commonly used for isolation on mains.

## Answer

A sluice valve (gate valve or cutoff valve) is the most common valve on water mains. It is used to fully open or fully shut off the flow, and is placed at junctions, at branches and at intervals along the line to isolate a section for repair.

```text
        hand wheel
           |
        spindle (screw)
          _|_
         |   |
   ======| | |======  gate (wedge) moves
         |___|        across the pipe
          body
```
#### Construction
- A cast-iron body and bonnet, bronze seat rings and a wedge-shaped gate (disc), moved by a screw-threaded spindle and operated by a hand wheel or key.
- The spindle may be rising (the stem rises as the valve opens, which shows its position) or non-rising (used for underground valves, operated with a key through a valve box).
- The end connections are usually flanged.

#### Working
Turning the wheel clockwise lowers the gate across the flow, closing the valve; turning it anticlockwise lifts the gate fully clear of the waterway, opening the valve with little loss of head.

#### Features
- **Advantages:** low head loss when fully open (the flow path is straight), tight shut-off, flow in either direction, simple and durable.
- **Disadvantages:** unsuitable for throttling (the gate vibrates and the seats erode), slow to operate (many turns of the wheel, although this helps against water hammer), and bulky and costly in large sizes.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What is a sluice valve used for?
   A. Completely opening or shutting flow
   B. One-way flow
   C. Air release
   D. Throttling
   Answer: A. It is a gate/cutoff valve. (Key point: Purpose)

2. How is the valve closed?
   A. Anticlockwise lowers gate
   B. Turning wheel clockwise lowers gate across flow
   C. Float falls
   D. Pulling a lever
   Answer: B. Clockwise lowers the gate. (Key point: Closing)

3. Why is head loss low when open?
   A. Narrow opening
   B. S-shaped passage
   C. Straight flow path
   D. Flap obstructs
   Answer: C. The gate clears the waterway. (Key point: Advantage)

4. Why is slow operation helpful?
   A. Helps against water hammer
   B. Saves time
   C. Increases noise
   D. Reduces cost
   Answer: A. Gradual closing limits surge. (Key point: Slow operation)