WEIGHT-MEASURING BED

PROBLEM TO BE SOLVED: To measure the weight of a patient and the variation thereof precisely through a simple and inexpensive arrangement by detecting the pressure difference between a main tank disposed on the underside of a bed and a standard tank communicating with the main tank via a pipe provided with an on/off valve. SOLUTION: This weight measuring bed 1 comprises an expandable/ contractible main tank 2, and an auxiliary tank 8 communicating with the main tank 2 through pipes 4-6 provided with on/off valves 9-11, 13-15 and 18-20. When the weight is measured on the bed 1, a pressure release value 24 is closed and all the on/off valves 9-11, 13-15 and 18-20 are opened so as to supply the air from a pipe 6a to both tanks 2, 8, thus equalizing the inner pressures. The on/off valve 20 is then closed under that state and a patient is laid on mats 3a-3c, and initial weight of the patient is read out by means of recorder 26. When the on/off valves 10, 14, 18 and 19 are closed subsequently, a pressure difference appears between both tanks 2, 8 due to the weight variation (increase or decrease) of the patient due to hemodialysis. The pressure difference is detected by means of pressure difference transmitters 12, 17 and recorded on a recorder 26, thus detecting weight variation of the patient.