Pre-action sprinkler head.

Peace of mind when installing sprinklers to water sensitive areas.

Gemini is a pre-action sprinkler head that effectively eliminates accidental release. The unit acts as a ‘double-knock’ system and will only release water when both heads have been activated.

Unintentional activation of a sprinkler system is very unlikely but unfortunately cannot be ignored. This often means that sensitive areas of a building where accidental release would cause severe water damage are left unprotected. Alternative systems such as pre-action installations or stand-alone gaseous protection have distinct drawbacks.

Pre-action installations are costly to install and maintain due to the additional equipment required such as additional pipework, detectors, releasing panel, dedicated alarm valve and air compressor. Pre-action installations are also not preferred for life safety applications. Gaseous systems have similar disadvantages and also take up additional space to store gas cylinders.

System Features

Cost efficient pre-action system requiring no specialist equipment or maintenance requirements.

Simple installation, uses same connections as traditional piping systems.

Gemini is easy to maintain, other pre-actions systems are expensive and require specialist maintenance.

No accidental discharge, additional safeguard when protecting water-sensitive equipment.

A sustainable, environmentally friendly alternative to gaseous systems.

Easily integrated into existing sprinkler systems with wet or dry pipework.

The Gemini System

When water-sensitive areas within a building (such as a server room) is to be protected, the use of Gemini pre-action sprinklers represents a simple and cost effective solution. These special sprinklers can be simply connected to the existing or planned sprinkler pipework to provide ‘double-knock ‘safety against unwanted water discharge, whilst offering the same fire protection as standard sprinkler heads.

With this system, the quick response heads operate in such a way that the first head to activate acts as a detector and will relay an alarm condition signal, alerting the building owner or facilities management. The second integrated head is engineered to act as a normal sprinkler head and discharge water on activation.

In an actual fire condition, both heads will activate and water will be discharged from the right sprinkler head only (see cut away diagram). This design minimises any delay and provides the normal benefits associated with reliable wet fire suppression systems and life safety quick response heads. In the case of only one head being activated by accident, no water is released.

System Components

Gemini sprinkler head

The pre-action sprinkler unit consists of a cast housing with two separately arranged sprinklers. The head is mechanically installed using a union coupling.

DSZ 3000 monitoring panel

The monitoring panel can monitor one or multiple linked Gemini heads and show their operating status.

Interconnect cable

Interconnect cables are used to connect several Gemini sprinkler head units together in parallel. A special end-of-line cable is used for the last unit in the run which, is then connected to the Gemini monitoring panel.


A Gemini system can be connected to an IMM and monitored via our Zonecheck Addressable controller (see Zonecheck Addressable brochure).


The Gemini sprinkler head is approved to VdS standards. Gemini facilitates easy compliance with LPC TB206 to sprinkler protect all areas of commercial buildings over 30m tall.

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Is Gemini approved

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Gemini is currently available with VdS approval.

What is Gemini?

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Gemini is a pre-action sprinkler head meaning that it has the benefits of additional protection against accidental water discharge (similar to specialised pre-action sprinkler systems) compacted into a single unit. Gemini features two sprinkler heads, both of these heads must be activated in order for water to be discharged (in a fire situation). Where just of the heads is activated, a fault alarm is generated but no water is discharged prevented accidental water release.

Where can I install Gemini?

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Gemini is designed for use where water damage from sprinkler heads is a real concern but the protection that the sprinklers provide is still required/desired. Typical uses are small server rooms/electrical rooms within lager buildings such as offices, retail, hospitals and transportation hubs.

How does Gemini connect to a sprinkler system?

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Gemini connects onto standard sprinkler pipework to connect onto the supplied 1” union.

Can Gemini be linked to a central fire alarm panel or BMS system?

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Yes, the stand alone monitoring panel has functionality to provide a fault relay output compatible with most any panel and systems including BMS.