Hop Trub Expansion/Space Calculation

[grassrootsvt]

In a few days, I'll be modifying my kettle in order to account for hop trub at the bottom of the kettle (flat bottom) when brewing double ipas and the like. My kettle is 45" is diameter and I'll normally be brewing 8bbls of wort.
By any chance, might someone have feedback on the expansion/volume of pellet hops? Typically, in the past, I would lose 1 barrel of wort when hopping a 7bbl batch of double ipa at a rate of 15 to 20 pounds of hops - or, I would lose 200 liters of wort to trub when brewing a 1200 liter batch of hoppy ipa. However, I suspect that someone here must have some experience or wisdom at their disposal?
My idea is to place a racking port on the sidewall of my single walled kettle, with an adjustable racking arm so that I can pull relatively clear wort without clogging my heat exchanger - among other things, I have an inline mesh strainer but, for the sake of discussion, I am curious if someone is more knowledgeable than I (very likely) and could present a formula or some theory behind the positioning/length of my racking arm.

[gitchegumee]

Maybe a hop back?

Your own experience will serve as the best guide you can find. I would think that losing 15% of your wort is too much, but I'm not brewing your beers. The best thing I can recommend is that you take the first 3/4 of your wort via your new racking arm, and then try to collect the remainder through the "normal" kettle drain and a hop back, which will clarify your remaining wort sufficiently. A hop back doesn't have to be complicated to be very useful. I'm just now switching to using whole leaf finishing hops in a hop back so that I may suck up the last few liters in the kettle, relying on the whole hops & hop back to filter out the pelletized bittering hops and trub on the way to the heat exchanger. I'll get a bit more wort, pay a bit less for whole hops, improve the clarity of my cast wort, and impart a nice aroma to my beers.

[grassrootsvt]

Hop Back suggestion

Hey there - I've used a hop back in the past - but there are some limiting factors which won't allow me to use one in this project. Namely, the amount of cold storage space that I have. Also, the fact that I have an exorbitantly expensive hop contract for pellets... But I agree with your suggestion and had pondered it in the past. Will continue to think it over... Thanks!