If you brew by hand, with simple brewing equipment, your gear has a greatly reduced start-up cost and will not break you financially if wear and tear occurs. However, we want your equipment to be as enduring as possible. For this reason we offer the following recommendations to help you troubleshoot maintenance issues with your equipment.
Mechanical brewing equipment that is ‘plumbed-in’ (connected to the water mains) tends to operate as a closed system, meaning there is no air inside the machines. As you may know, air is easily compressible, but water is almost impossible to compress. Water does expand when it heats up, however. Positive pressure will build up in brewers that are full of water, and this can present dangers to anyone operating or servicing equipment without proper training. In some countries, it is common that insurers require cafe operators to conduct annual pressure testing in order to comply with their policy guidelines. The key to good practice is to never service equipment when it is hot or the power is switched on. The incoming water supply needs to be accessible and should have an isolation valve that allows baristas to cut off the flow of water in case of any unforeseen leaks.
Illustration of an isolation valve.
Cracking and Crazing
Many materials used in manufacturing filter cones and brewing machines are polymers derived from silicon and latex. The most common are rubber and silicone. There are also many plastic polymers such as acrylic and polyethylene, all of which are manufactured through a process known as polymerisation. The polymerisation process joins molecules together to form a compound that takes the shape of a long chain.
Note: Silicon is an element, silicone is the polymer made from it, and silica is the mineral ore we get silicon from.
Over time, in coffee applications, rubber has a tendency to become stiff and brittle, and silicone has a tendency to become soft and sticky and to appear cloudy in colour.