GEZE lead way in TechTalk

GEZE UK’s technical team is renowned for its encyclopaedic knowledge of legislation and regulations as well as its ability to find innovative technological solutions for architects, specifiers and contractors. Here we feature some of the most frequently asked questions… Q: Which door closer would you recommend to assist with compliance in relation to the opening force requirements for disabled people? A: There is not a straightforward answer to this question because the answer will depend on the door type (fire or non-fire), leaf width and weight, external or internal door, opening angle requirements, surface or concealed mounting, floor or overhead closer and of course budget constraints. As a starting point, an electromagnetic hold-open or electromagnetic hold-open with a free-swing door closer would be recommended to allow maximum freedom of movement for disabled people. If the budget allows, automation of the door would ideally be recommended. For manual door closers most manufacturers offer a range of standard V (scissor) arm closers, guide rail closers, concealed closers and if required floor closers that can assist towards compliance. Q: I have an arched head door. Do you have a closer that will work? A: If the arch is quite shallow then it is often possible to use an arched door drop plate with a conventional V arm door closer fitted in figure 1. Again, a CAD drawing should be provided by the enquirer to check the geometry and ensure that the proposed solution will work. If the arch is sharp then a floor closer with pivot lever arm would be recommended. This option is also ideal for existing hinged doors that require controlled closing where the end user does not want to see a surface mounted closer. Q: I have rebated doors. Do you have door closers to suit? A: If the door set is fitted with an independent door selector then all types of door closers will function. Either overhead surface mounted, overhead concealed or floor mounted are available with integrated sequence control and also electro-hold open versions with integrated sequence control. Note: a carry bar is still required. Q: I have an air pressure of 50 Pascal. Which door closer do I need? A: First establish whether the air pressure is positive or negative. Positive pressure acts against the closing force and negative pressure assists the closing force. If the pressure is positive, a Nm torque to Pascal formula should be used to calculate the required Nm closing torque to overcome the positive pressure. If the pressure is negative then the closing force and the closing speeds (including the latch action) must be adjusted to accommodate this pressure. Q: My door is fitted onto parliament or offset hinges. Can door closers work with this arrangement? A: The offsets can vary considerably but in general the maximum is usually 100mm. This offset does not have an effect on surface mounted or concealed overhead closers. If necessary a CAD drawing would be requested by the supplier to overlay the closer onto the drawing and check the geometry to ensure that it will work. Q: I am specifying electro hold open closers. What are the electrical requirements including the size of power supply required? A: For the most popular electro hold-open closers, the supply voltage is 24V DC. The current consumption will depend on the type of closer used. A typical consumption ranges from 35mA to 110mA per closer. The simple rule of thumb is to multiply the total number of closers by the mA value specified by the manufacturer and divide by 1000 to get the current in amps. Voltage drop in terms of cable conductor sizes must be taken into account and therefore it is often easier and more cost effective to use several smaller power supply units than one large capacity unit. If you would like to ask GEZE UK's technical team a question to be featured in the next edition of Access please email us at access@geze.com. Alternatively for an

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