ANSI FCI 87-1 pdf free download

ANSI FCI 87-1 pdf free download.Classification and Operating Principles of Steam Traps.
3.2.2 Valve Lift
The formula in paragraph 3.2. I assumes a full open orifice. In a steam trap this is not necessarily true. The fact that, in some stream traps, the valve does not lift fully to the equivalent free area of the orifice does not imply poor design. It, however, makes comparison of steam trap capacities on orifice diameter alone unreliable.
3.2.3 Pressure Before and After the Orifice (Pressure Drop)
The theoretical how in 3.2.1 is based on the difference in pressure immediately before and immediately after the orifice, which is also called pressure drop.
In a steam trap. the body and the mechanism of the trap offer resistance to flow, and the pipe connections on the discharge cause similar interference. So, in practice, the pressures at the orifice proper are rarely, if ever, known and are variable, with a corresponding effect on discharge capacity.
3.2.4 Density of Water
The density of water as compared to steam is another ftictor to consider. At typical atmospheric conditions, the density of water is 62.3 lbs/ft3 and for steam it is .037 lbs/ft3. Therefore. 1 lb of steam at typical atmospheric conditions occupies a volume of approximately 1700 times that of water.
3.2.5 Temperature and Phase Changes Relative to Discharge Capacity
Discharge capacity of condensate through a steam trap is most seriously affected by the physical changes that take place.
When discharging to atmospheric pressure, the physical state of water normally does not change as it flows through an orifice or a trap, provided the temperature is below 2 1 2°F at the inlet. Condensate above 212°F at the inlet, when reaching atmospheric pressure, cannot retain all of its heat and some of the heat causes “flash” steam to he generated. The result is a considerable increase in the specific volume and a corresponding reduction in the density of the mixture of steam and water flowing through the orifice.
The theoretical effect of “flash steam generation can be seen in Table 1, showing the volume of 1 lb. of condensate following release to atmosphere from various upstream pressures and temperatures.
From Table 1, it can be seen that atmospherically discharged saturated condensate at 250°F hashes and expands to 86 times its original volume at the inlet. At 3(X)°F it expands to 140 times, and at 350°F it expands to 216 limes its volume at the inlet. This considerable expansion of the condensa and flash steam mixture seriously interferes with the flow of condensate and reduces the discharge capacity. The impact of this reduction can be seen by comparing the theoretical flow of water through a one square inch area at various temperatures and at a pressure differential of 1(X) psi. (See Table 2).
These figures clearly demonstrate how specific steam trap discharge capacity figures can he misunderstood unless the pressure and temperature of the condensate at the trap inlet and trap outlet are known.
3.2.6 Effect of Steam Trap Operating Principle
A typical steam trap is not just a simple orifice hut includes an Integral, self-actuated valve operated either by temperature difference. buoyancy. or change of phase. This fact must be taken into consideration when comparing steam trap capacity ratings.
The capacity of all steam traps increases as the condensate temperature is lowered. Not all steam traps will, however, discharge condensate at steam temperature. Some traps, while being capable of operating at steam temperature, have their best condensate discharging characteristics at lower temperatures.
It would, therefore, be impossible to fix an arbitrary standard temperature at which all steam traps should be tested. Thus, each manufacturer determines the best operating temperature range for their product, and the resultant capacity ratings are only meaningful when based Ofl this stated operating temperature. For this reason. manufacturers who use this standard will state operating temperatures for each published trap capacity.ANSI FCI 87-1 pdf download.