PECM Issue 31 2018 | Page 161

Valves & Flow Control ROTARY VALVES FOR FOOD APPLICATIONS ortunately nearly all food product characteristics are easily managed within Rotary valves and the basic design of the valve can remain relatively simple without compromising hygiene and ease of use. F Common product characteristics including being sticky and cohesive have a tendency to ‘build-up’ on the swept surfaces. Most foodstuffs are biodegradable. However, some do not post a hygiene risk as they represent or contain a sterlising or preserving agent; such products include sugar, salt and chocolate and a standard rotary valve construction only is required. Other products that have a long storage life, providing they remain dry, also do not require special features especially if they will be further processed by cooking. Flour and rice are typical examples. In all these cases unless there is corrosion risk, cast iron/carbon steel would suffice, however most users now require stainless steel, as a matter of course. High sensitivity materials such as baby food products and high fat milk powder require a higher degree of contact surface finish and integrity, often polished to a mirror finish. Most food ingredients are potentially explosive in dust form and will be subject to the ATEX Directive. Whenever a valve is required to act as a flame containment device, regardless of pressure condition or external environment, then it automatically becomes categorized as an Autonomous Safety System requiring certification of a Notified Body who must approve the technical file and manufacturing procedures, Email: [email protected] Web: www.rotaval.co.uk Made in Britain Issue 31 PECM 161