PORTSMOUTH, N.H. — The sister of a man who was killed in a keg explosion at a New Hampshire brewery two years ago has filed a federal lawsuit against three companies involved in the manufacture and distribution of the keg.

The Portsmouth Herald reports M. Christina Kettering says the keg was negligently designed and didn’t feature adequate safety warnings. She also says a device installed in the keg to prevent overpressurization failed to work as designed.

Benjamin Harris of Newington was emptying a plastic keg with pressurized air at Portsmouth’s Redhook Ale Brewery when it blew apart in April 2012, killing him. Kettering’s suit was filed in federal court in Concord on April 1.

Keg maker Plastic Kegs of America, distributor Satellite Logistics Group, and safety device maker Medway Plastics Corp. deny the allegations. They suggest Harris, or others are to blame.

The defendants say Harris’ “comparative negligence” bars the lawsuit because he was, or should have been aware of “the nature and risks of the keg” and that he assumed those risks. Redhook is not named as a defendant.

A jury trial has been scheduled for Sept. 1, 2015.