M.E. Simpson Co., Inc. leads the industry in field testing services for hydraulic studies. Our firm manufactures the Polcon® equipment used in our specialty Polcon® Services. These hydraulic services will provide your Utility with practical field data that can be applied in maintaining your distribution system’s proper hydraulic flow and other critical issues.
Polcon® Flow Monitoring Equipment and Pressure Recorders can be used for large flow meter testing, C-factor testing, pump curve testing and analysis, and long term flow measuring such as District Metered Areas and other flow evaluations in distribution systems.
In order to take full advantage of the use of the Polcon Flow monitoring equipment, certain rules of thumb need to be applied for test sites. The diagram below describes a general approach to the test site needed for correct flow measurement. Other test sites can be considered but only after a field evaluation has been performed to determine site suitability.
At each test site the Utility must provide a 1” corporation stop that is located 10 pipe diameters from any type of obstruction, valve, check valve, reducer, elbow, or tee. It is possible to use existing corporation stops that are 1-1/2” or 2”, provided they have proper upstream and downstream lengths of pipe to provide conditioned flow. The corporation may be located either upstream or downstream of a meter. In the case of testing raw water meters using pitot equipment, the recommended location of the test corp can be before or after the meter, but it needs to be after the Low Lift pumps in order to have positive head.
If the corporation stop cannot be installed inside a building due to piping configurations or space limitations then it must be installed outside below grade, in a vault, with a minimum 48-inch diameter. The manhole opening must be directly over the corporation stop if the vault top is less than 30 inches or [the diameter of the pipe plus one-foot] from the corporation stop, whichever is greater. This is to allow for sufficient room for installation of the pitot rod and pipe caliper. If a vault cannot be installed then the Utility must provide a trench box, shoring, or an excavation that meets OSHA trenching standards.
If the corporation is not direct tapped but is installed in a saddle tap setting, then it is very important that the pipe be drilled with a 15/16” drill bit. The standard 7/8” drill bit will not provide a large enough diameter hole. The pitot equipment (rod and caliper) will not fit through a hole smaller than 15/16 of an inch.