1. A pumping device that contains: a first domed portion attached to a second domed portion； a flexible membrane located between the first domed portion and the second domed portion, thereby forming a first chamber between the first domed portion and the flexible membrane, and a second chamber between the second domed portion a part and flexible membrane, a vacuum source connected to the pumping device in order to create a vacuum in the first chamber and draw the fluid into the second chamber； and a regulator connected to the pumping device, wherein when the vacuum source is disconnected from the pumping device, the regulator is operated to open the air passage in the first domed portion in order to control the rate at which the fluid is pumped out of the second chamber. 2. The pumping device according to claim 1, which further comprises a bag located in the second chamber for receiving the fluid. The pumping device of claim 1, wherein the flexible membrane is a bag. The pumping device of claim 1, further comprising an enteral feeding tube coupled to the pumping device for delivering a fluid to a patient. The pumping device of claim 4, wherein the enteral feeding tube is short to allow placement of the pumping device close to the patient. The pumping device according to claim 1, wherein the pumping device is not electrically driven. The pumping device according to claim 1, which further comprises a volume indicator located on the pumping device for measuring the number of1. Насосное устройство, которое содержит:первую куполообразную часть, прикрепленную ко второй куполообразной части；гибкую мембрану, расположенную между первой куполообразной частью и второй куполообразной частью, тем самым формируя первую камеру между первой куполообразной частью и гибкой мембраной, и вторую камеру между второй куполообразной частью и гибкой мембраной；источник вакуума, соединенный с насосным устройством для того, чтобы создавать вакуум в первой камере и втягивать текучее вещество вн
