Difference Between Manual Pull and Key Switch

This article will explain differences between Manual Pull and Key Switch which both are normally found in fire protection system. Both are used to trigger CO2 cylinders to release gas into the protected area.

Manual Pull

1. Manual pull is mechanically operated device used to activate CO2 cylinders. There is a handle and wire rope connecting handle and solenoid valve. By pulling the handle, solenoid valve will be mechanically operated to release CO2 gas.
2. When operated, there is no pre alarm, no second alarm, no fire curtain drop and no ringing at alarm bell. 
3. That the reason, manual pull is considered secondary back up in case of automatic system (heat and smoke detector) is not functioning during fire.

Manual Key Switch

1. Key switch is electrically operated device used to activate CO2 cylinders. By turning the button clockwise or pressing the button, electrical signal will be sent to solenoid valve to activate CO2 cylinders.
2. When operated, electrical signal will be sent to CO2 panel.
3. Key switch is considered primary back up in case of automatic system (heat and smoke detector) is not functioning during fire.

Manual Key Switch

Testing & Commissioning Fire Protection System

Before detail explanation given on how to conduct T&C for Fire Protection System, let introduce overall concept of installation adopted.

The system consist of 4 CO2 Panel in which every of them have the followings.

1. Heat detector
2. Smoke detector
3. Fire curtain
4. CO2 gas cylinder

Procedure of Testing shall be as follow.

1. Check whether installation is completed as per drawing or not.
2. Check physical installation whether any defect or irregularity observed.
3. Start with Lamp Check for panel - To ensure all indicators are functioning well.
4. Check Battery and Charger condition.
5. Test Heat detector - Apply heat ( normally using lighter) to heat detector. Check whether detector triggered or not. If detector triggered, signal will be sent to CO2 panel and indicator light will lights up at CO2 panel. Bell will start ringing.
6. Test Smoke detector - Apply smoke tester by spraying smoke to detector. Second alarm will comes in and CO2 panel indicator will indicates light.
7. At this moment, fire curtain will drop down.
8. After 30 Seconds, CO2 gas will be released from CO2 cylinders. Gas will be flooding room area and  to cease the fire.
9. Reset alarm after attending the fault.

Smoke Detector Tester

Fire Curtain

Manual Key Switch

Solenoid valve

Note and Precaution.

1. Solenoid valve connection at CO2 cylinder shall be isolated to avoid actual release of the gas during activation. Unless, actual testing is required and spelt out in B.O.Q.
2. However, in order to check signal to solenoid valve, a voltage test can carry out. A 24V signal will be recorded when signal from CO2 panel sent to solenoid valve to release CO2 gas.