How do you keep your def from freezing or getting to cold in your supply tank that sits on your job? We have fuel trailers that sit on our jobsites that have a def tank on them to and on 2 of our trailers the filters Brooke and drained a bunch out. Would a stainless filter and filter head fix the problem they are plastic. When this happened it was down around zero with wind chill of -19.
Here's what I found at http://www.discoverdef.com/def-overview/faq/#freeze Diesel Exhaust Fluid (DEF) freezes into a crystalline slush at 12°F (-11°C) and should not be kept at temperatures above 86°F (30°C). If DEF is frozen on your vehicle, for example overnight or over a weekend, you do not need to take any action. Use the vehicle as you normally would. Truck manufacturers use a variety of heating methods to thaw frozen DEF tanks, including in-tank heating elements. While the thawing process is taking place the vehicle's performance will not be affected (the amount of DEF used will be reduced because a cold engine produces a low level of NOx emissions). In some cases the DEF supply tubes are also heated to prevent freezing or tubes are emptied once the engine is turned off. Looks like some sort of heat tape or insulation for a DEF tank & hoses are in order. Wind chill doesn't matter. It's the actual temp of the DEF. In your case it was zero and DEF starts to freeze at 12 degrees. I expect DEF in the filter actually froze at zero. The tank may not have frozen solid because of the larger volume. Given enough time though, even the tank would freeze.
Thank you here is a picture of what happened I was thinking that possibly that could have been the weakest part of the plumbing and when it got cold it got brittle and so that is what broke.
No getting around it, in those temps you will need some way of heating and keeping the DEF above the freezing point. Using Stainless may help some but I cant guarantee it wont break as well. I do not know what the expansion rate is but being 66% water it probably expands enough to cause damage. Also all that spilled DEF will cause everything it contacts to now corrode. Did you build your units yourself or were they from an outside vendor? There are a lot of considerations to be made when building DEF distribution units. Everything has to be DEF compatible and many of the units made for this purpose have heaters built in. Oh and wind chill makes no difference, 0F is 0F no matter how fast the wind blows.
Remember that DEF is a salt. It will corrode any unprotected metals. A wash in the early Spring after the freezing weather or before in a heated space will prevent damage. ( I wash and oil my fertilizer spreader after use and it still rusts.) Since DEF is mostly water, I expect even a SS filter body would break when frozen .. unless there was room to expand. A long time ago, a HS science experiment demonstrated water breaking a heavy wall cast iron ball. It was filled, sealed, placed into a freezer. The next day a big chunk of the side was broken free. I wonder if a rubber ball in the filter would be enough to allow expansion without damage. But then you have a frozen filter and no flow through it...
https://www.toteheater.com/featured-ibc-tote-heating/tote-industry-news/ We use a DEF tote heater, similar to the one in the link above. It has worked well, even in temperatures below -30C. The blanket keeps the pump and tote warm, so nothing freezes. I don't believe that a stainless filter housing would withstand being frozen. If everything is frozen, you still would have to thaw it out in order to use the DEF.
The fuel trailer i was using had a stainless cim-tek DEF filter. It's been down to ~10° F a few times and nothing blew out. I tired to get all the DEF into equipment any time it was forcasted to get below 15° F. The tanks on equipment it are designed to deal with it freezing and have heaters. It's a lot easier to deal with when the trailer only carries 120 gallons and we were burning through that every 3-4 days.