PROJ00507 - Laserfiche WebLink

Home Browse Search

I I I I I I I I I I I I I I I I I I I used. Thi s results in an average daily demand of 185 gpm. A revi ew of relationships between average and peak demand rates was performed. This resulted in estimated peak daily and peak hr)IJr1y rates of aporoxill1ately 550 and 1,200 gom, respectively. It is necessary to verify that the computer program adequately predicts flows and pressures in the system. Thi s task is greatly hampered by the 1 ack of simultaneous demand and flow measurements. There are few recorded oressure measurements; however, the demand rates at the time these measurements wel'e made are unknown. The best pressure readings available are at the four oressure reducing valves (PRV's) locations as shown in Figure 4.1. These measurements are given in Table 4.1. =============================================================================== Table 4.1 Pressure Reducing Valve Measured and Computed Values PRV Number Measured Pressure (psi) COlllouted Pressure (psi) Upstream Oownstrea1'1 IJpst,..eam nownstream 1 89 40 Cl6 47 2 98 95 71 78* 3 no 108 129 108 4 100 100** 104 104 ------------------------------------------------------------------------------- ------------------------------------------------------------------------------- * PRV Closed ** Bypass Operating For the verification of the computer program, the downstream set points of the PRV's were adjusted to cause the same pressure drop as was observed for the measured conditions. There is good agreement between the measured and computed pressures with the exception of PRV Number 2. This valve is located in the far eastern distribution loop on a 2-inch PVC line. The progral'l computed a downstream pressure more than the upstream pressure. Consequently, the valve would be closed. It is believed that the existing valve at this location may be stuck or the pressure measurements are in error. 4-3 1062c