Every Employee an Owner, Every Customer a Commitment If you need a sample cooler or sampling equipment for steam/water, gases, liquids, slurries or bulk solids, you have come to the right place. Sentry has over 80 years e......Every Employee an Owner, Every Customer a Commitment If you need a sample cooler or sampling equipment for steam/water, gases, liquids, slurries or bulk solids, you have come to the right place. Sentry has over 80 years experience in manufacturing sampling components and sampling systems. We also manufacture compact heat exchangers and boiler blowdown heat recovery systems.