We routinely collect liquid hazardous waste in 5-gall containers in our laboratories.  This waste stream primarily consists of flammable solvents and water.  Full containers are moved to our bulk haz waste accumulation room and transferred to 55 gall drums.  The 5-gall containers are very heavy so lifting/pouring can easily lead to spills.  We have found that hand pumps also tend to be messy.  Does anyone use a mechanical pump (intrinsically safe, possibly air driven, or other) to manage this type of transfer?