Hydraulics for Fire Protection
Hydraulics for Fire Protection For most NFPA 13 systems is conservative without accounting for the velocity pressure. Most scenarios where velocity pressure would become a concern with an NFPA 13 system are self-regulating because of the high friction loss values that typically accompany the high velocities. It is permitted to use the velocity pressures though for any system and may prove beneficial if the calculation is close to what is available from the water supply.
Atmospheric pressure is the weight of air in the atmosphere over an area. 14.7 lbs is the weight of a one inch square column of air as tall as the atmosphere measured at sea level. The change in atmospheric pressure may be important when installing a system at high elevations. In many cases it is not necessary to use atmospheric pressure in calculations done for sprinkler systems. However, there are times when the absolute pressure will need to be used and therefore the atmospheric pressure must be accounted for in the equation.
Gage pressure is the pressure read off of a gage. It does not include atmospheric pressure as the atmospheric pressure is also acting on the gage. Absolute pressure is the sum of atmospheric pressure and gage pressure. In a few equations, it is necessary to use the absolute pressure in order to arrive at a correct answer.
You can also Read Surface Production Operations: Vol 2: Design of Gas Handling Systems and Facilities
Hydraulics for Fire Protection Content
- Definitions and Equations
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- Hydraulic Calculation Principles
- Hydraulic Calculation Process
- Example Calculation
- Review of Computer Calculations
The amount of pressure available from a water tank is important to know. The measurement is to the water line because we are trying to determine what the gage will read.
There is much fluctuation from gage needles or interpretation between marked values that a whole number is the appropriate level of accuracy.
Flow Equation one of the basic equations utilized in the industry. Most flow meters work on the concept of measuring the velocity of water flowing past a point and knowing the diameter of the opening. From this equation, the meter would then calculates the flow.
Units are important when working with this equation, as flow is more common in the sprinkler industry in gpm and not ft3/sec
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