An actuator is a type of motor for moving or controlling a mechanism or system. It is operated by a source of energy, usually in the form of an electric current, hydraulic fluid pressure or pneumatic pressure, and converts that energy into some kind of motion (Wikipedia). In building services engineering there are two types of actuator we commonly use, valve actuators for controlling valves within BMS systems and actuators for controlling ventilation equipment or automatic opening windows.
SCS Group, as a control and fire engineering specialist provides both types of actuator, the BMS type as part of our design and installation service for control systems, further information is available here http://www.groupscs.co.uk/overview/.
Actuators for smoke control are part of a system containing 3 elements: A trigger, an actuating mechanism and a power source. The trigger for automatic opening systems will usually be a smoke detector. A range of smoke detectors are available from the SCS online shop, the most popular being the optical smoke detector.
Actuating mechanisms are most commonly electrical actuators, pneumatic systems used to be popular but the noise and space taken by compressors led to the decline of these products. The most commonly used actuators are the chain drive, the linear actuator and the folding arm. The selection of the actuator is dependent on the stroke required to open the ventilator or window to achieve the required free area, and the power needed which is a function of the weight, the angle of installation and the hinge position of the ventilator.
For most smoke control uses a back up power supply is required and most commonly this is a battery back up system with 24V actuators although it is possible to use Uninterruptable Power Supplies and 230V actuators. A packaged local control panel designed for use with AOV’s is the easiest way to achieve a Building Regulations compliant solution.
An override switch for testing and for Fire Brigade use for fire fighting systems is also a requirement of building regulations as this is often the only operator facility for the system it is useful to have some system status indication and warning alarms for fault or loss of power to ensure the system is maintained correctly and ready for use when needed.
For environmental ventilation systems, actuators are similar to those used for smoke control but may be made from composite material and are unable to withstand high temperatures. Sophisticated control systems may be applied in buildings where control of the internal environment is important such as schools and commercial buildings for example Windowmaster’s MotorLink™ system. Motorlink technology communicates with every single window motor in the building, providing precise motor control and monitoring of every motor and delivering genuine synchronisation of several motors in the same window, error reporting, reverse functions and online parameter setting.
To purchase quality actuators online at competitive trade prices visit the Easivent ecommerce site www.easivent.co.uk If you require advice on smoke control or ventilation systems then visit the SCS Group site www.groupscs.co.uk
This is a great tool when looking at designing Smoke Ventilation Systems in Flats. Easy to understand and use.
Smoke Ventilation is often perceived as “complicated” but not any more, the SCS Group provide a range of easy to understand documents to help you or can provide expertise if required.
The documents can be found on the downloads section of the SCS Group website…..recommended!!
And to make it even easier all the items required to install a Natural Smoke Shaft System are available on the Easivent Website…..simple!!
An automatic opening vent or AOV is a commonly used method of smoke control to lobbies and stairwells of tall or large buildings to comply with the requirements of Approved Document B of The Building Regulations. Automatic opening vents are specified by the free area they provide and the general rule of thumb is that vents within lobbies should have a free area of 1.5m2 while stairwell vents should be a minimum of 1.0m2. Appendix C of Approved Document B specifies how the free area is calculated, this being either;
- The delared aerodynamic free area in accordance with BS EN 12101-2 – Smoke and heat control systems – Part 2: Specification for natural smoke and heat exhaust ventilators; or,
- The total unobstructed cross sectional area measured in the plane where the the area is at a minimum and at right angles to the direction of flow (see diagram)
The commonly used solutions are either;
- a proprietery ventilator with the actuator already fitted, for example a louvred ventilator like the Easivent glass louvre or for stairwell vents a roof hatch type which can also be used for roof access where required, such as the Easivent AOV.
- An opening window of the correct dimensions equipped with an electrical actuator. Commonly used actuators include chain drives, linear motors and folding arms. The actuator must be selected with regard to the weight of the window and the amount it must be opened to achieve the free area required.
The chain drive is the most aesthetically pleasing but has lower force than other types. The folding arm has high force and is unobtrusive and can open very large windows and hatches. Linear drives protrude into the space so may not be suitable for windows but are economical and powerful. For smoke control purposes actuators are usually 24VDC and provided with a matching control panel with a battery backed supply like the Easivent SHEV 3 control unit. Automatic opening ventilators are triggered by smoke detection within the common lobby. The full range of smoke control products are available at low cost for fast online purchase on the Easivent website.
By Easivent Products Manager – Mike Washbourne
Easivent customers where recently asked what was the main reason for them continually coming back to us. This could either be a preferred product or a service offered by the company. The answers are listed below in not specific order…..interesting!
- Unique high power folding arm actuators providing 140⁰ opening
- Low cost chain actuators
- Slit actuators
- Good range of rack & pinion actuators & linear actuators
- Competitive pricing structure
- Ease of installation of the modular control panels for BRE shaft systems
- Capability to produce bespoke control panels utilising addressable technology and inverter speed drives
- Wide range of switches, wind/rain sensors, detectors
- Next day delivery on most items
- Quick response to all technical queries
If you have not the seen full range of ventilation and control equipment we can offer have a look on the Easivent Website or contact me by e-mail
By Easivent Products Manager Mike Washbourne
On a recent project we were asked to provide an AOV smoke vent to a stairwell but also had to provide some natural light. A Velux window was chosen to provide the opening and this was operated via a chain drive actuator. It became apparent that the Velux Smoke Vent was also causing the stairwell to heat up as the positioning of the building meant the sun hit the window at its highest point during the day.
The client did not want a manual switch to be used to open the window during hot temperatures as this could be accidentally left open. This issue was easily solved thanks to the control panel we had installed which allowed us to connect a high level tamper-proof thermostat and a wind/rain sensor which would prevent water ingress through the Velux window during bad weather. The temperature control system is always overridden by a fire alarm signal so the operation of the smoke ventilation system is never compromised.
All the controls installed are available on the Easivent website and are highly recommended as a simple solution for this problem.
For more information please e-mail Mike Washbourne at Easivent Smoke & Ventilation Products