Observe the apparent first check valvedifferential pressure (a - b).
观察第一止回阀压差(A - B)。
2
Measure and record the differential pressure across the valve using a Watts Series PG meter. CAUTION: Safety glasses should be used.
采用美国瓦茨系列PG仪器测量和记录通过阀门的压差。警告：应该使用安全眼镜。
3
Requirements: the pressure differential relief valve must operate to maintain the "zone" between the two check valves at least 2 PSI less than the supply pressure.