Grease build up in Non Return Valves
BLUF: Can any of you geeks point me towards any discussions or case studies on the effect that fat, oil and grease (FOG) has on (NRVs?). I’m guessing it’s not going to be good but I need to know how bad it could be, maintenance periods, dosing options.
Background:
I’m working on the adaptation of the drainage for an existing department store in London. Over the years the store has developed a maze of drainage, both foul and rainwater, no-one really knows how it works and there is a history of FOG build ups causing blockages, and being London concern regarding rat ingress.
There are around 20 proposals to fix all the issues. Two of these are flap type NRVs to prevent rat ingress, and grease traps with a wider grease management process. However, there are areas where in the short term (2-10years) we will not be putting in grease traps for commercial reasons and so there is concern over whether fitting the NRVs to this section would make grease problems worse. The store doesn’t have a great record of maintaining the system so “just check regularly to prevent blockage” probably won’t be successful.
Optimistically I’m hoping that the pressure required to operate the valve may be enough to clear any FOG build up but I guess this would depend on what volume and the frequency of flow, and what type of valve we specify.
Holdfast Training Services Trial Blog 
How about this http://www.aquobex.com/products/flusher
That’s the product we’re looking at Doug but we need to justify this (as opposed to just an NRV) on top of the grease management training, grease trap, and dosing. The extra spend for the flusher units will only be justified if we can show that the NRV will block without the flusher unit, otherwise it just looks like we’re chucking the kitchen sink at it………which we are.