MICROFICHE REFERENCE LIBFUUW - Cd3wd.com

63The IRRI design has a handle bar which serves as both a supportwhile pumping and a handle for carrying the 45 lb pump. It is easy torepair and simple enough for small machine shops to construct. Designdrawings are given free of cost to manufacturerswho agree to IRRI con-ditions. Although this design is expected to be rugged for a longservice life, additional work is being done to improve its presentdurability (Kuether, 1975). No cost estimates were available and normalmaintenance consists of canvas repair after about 175 hours of use. Theperformance of this pump is reported (IRRI, 1975) as:40 gpm at 1.6 ft head32 gpm at 3.3 ft head29 gpm at 5.0 ft headThis, of course, will vary depending on the operator.The second form of diaphragm pumps is similar in operation to thepiston pump, however, as shown in Figure 3.16, the diaphragm is attachedto both the piston and the cylinder. This has the advantage of removingthe sliding friction between piston and cylinder wall. In addition,since the piston only serves to reciprocate the diaphragm, abrasive fluids,e.g. sandy water, can be pumped without wearing the piston and cylinderwalls.The common forms of dianh+aum r-- -=--pi55 ton pumps are opG, --ted -in- eitherof two ways. The piston can be reciprocated by a mechanical driver (e.g.gas or diesel engine), or for smaller capacities by hand or foot levelmechanisms (Figure 3.30) . The other method, is to utilize compressed airor hydraulic pressure on one side of the diaphragm to push it down and thenallow a spring loaded piston to pull it us. The pneumatic or hydraulicpressure is automatically regulated to provide the reciprocating motion(e.g. by a solenoid valve and regulator).