What is a Steam Trap?
A steam trap is an automatic drain valve designed to distinguish between condensate and steam, storing steam while discharging condensate under different tensions and loads. Furthermore, steam traps must have the capability of venting non-condensable gases quickly while protecting existing steam supplies. We offers steam traps from Armstrong, Barnes & Jones, Hoffman Specialty Illinois Marsh Mepco Nicholson Spirax-Sarco Steamco Sterling Watts to meet every steam boiler need. Steam traps can be divided into five main categories – Armstrong Barnes & Jones Hoffman Specialty Illinois Marsh Mepco Nicholson Spirax-Sarco Steamco Sterling Watts with many variations such as float-and-thermostatic bucket inverted bucket liquid drain radiator thermodynamic and thermostatic industrial types – that can help ensure water flows freely from boilers into condensate reservoirs when needed and closed when steam has been present – these should only open during these instances when necessary and should close once steam has been present.
Why Steam Traps are used?
Steam produced from a boiler contains heat energy that is utilized for creating heat for products. If it cannot do this due to warming materials, condensation results. When this heat escapes through fittings and pipes it turns into condensate that must be eliminated immediately to restore system performance and transfer of heat efficiently; accumulation in steam systems could even result in physical damage through corrosion or water hammer.
As illustrated by the accompanying sketch, condensate collects in horizontal pipes where steam flows through them, collecting as it builds to form solid slugs of incompressible water which travel at high speed until stopped abruptly by pipes, valves or fittings causing mechanical injury to them.
Let’s get right to it with some steam-trap advice.
F&T traps should not match the diameter of their pipes. I was inspecting one such trap located at the middle of a 6 in main that reached 35 stories in a building – its correct size should have been 1-1/4″ The trap was much too large to work efficiently; an over-sized F&T trap cannot open to collect the tiny amounts of condensate it must manage. When I inquired as to why this trap was so large, the engineer was taken aback; I asked why and he replied that 1 1/4-in. would have seemed ridiculous in comparison.
All traps need Delta-P
All traps need a change in pressure for condensate to move through them and out the trap, thus creating the “delta-P”. When exchanger control valves close, no steam pressure remains to move the condensate out; then when air enters through vacuum breakers inside shell, tension created between heat exchanger and steam trap creates necessary pressure that pushes condensate out through steam trap, thus creating this delta-P.
Beware of backpressure
At the exit side of your trap, be aware of its exit point as well. Does condensate need to travel uphill from there? If yes, check and monitor backpressure valve. When choosing the size of trap to purchase, this factor must also be considered when making decisions on its size and configuration. Also inspect any connected items connected to its outlet: Are other steam traps operating correctly, are flash steam injection lines being created within this line leading back into it causing backpressure as a result?
Traps don’t vent air
Air passes through a trap before being directed back into its original line; once returned it needs an exit route otherwise steam won’t travel as desired. If the discharge from a trap points upwards it forms a water seal which prevents air escaping through sealed lines (think about Sink trap) while steam wouldn’t have any way out either!
Be wary when using bucket traps near pressure-reducing valves; for them to work effectively they require being filled with water beforehand. As pressure reduction lowers steam’s pressure it creates superheat which in turn requires extra Btu be moved elsewhere; such as through bucket trap’s primary water which then converts back to steam before exiting. Without such prime trapping devices in place this would result in hot steam being expelled through lines returning back through them which is why thermodisc-type traps are typically seen at PRV stations.
Do not block lines that connect into gravity-wet returns. A gravity system does not use condensate pumps or boiler feed pumps, while an electric steam heater requires an air vent at its outlet in order to extract air. In contrast, condensate flowing into wet returns should simply flow freely by gravity into its line without needing traps – installing traps would result in condensate seeping through into your heater instead.
Certain traps allow condensate to rapidly change back into steam when it reenters their return line, particularly F&T traps as they cannot understand the heat content of condensate deposited therein and thus dump it at saturated steam temperature resulting in some of it returning as steam once it arrives back at their line of return. Backpressure creates issues in other traps and may compromise performance in other ways. When placed near a receiver of a vented boiler-feed pump and flash steam is released from it through its vent, puffs of steam appear from it. It could potentially provoke Knuckleheads into placing obstructions along its path; reduce steam pressure in order to stop flash steam. Given most steam heating systems already operate under high pressures it might make sense for us all to work towards eliminating it completely.
Radiator traps typically last 10 years before needing replacement. On average, their radiator will cycle 175,000 times each year; at that point it is time to retire the trap. If it remains closed it won’t provide heating; people may not even notice. But if left open and heated by an open radiator it could continue warming continuously while users continue without complaint; but now steam will return lines creating backpressure on other traps in your system.
Master traps make no logical sense. Installers often mistakenly believe they can solve all issues by installing one large trap at the inlet to their boiler feed pump – thinking this area as being like the tree trunk – while failing to understand why traps are located elsewhere or how radiator traps create pressure points within their systems, creating pressure points in turn and so resolving their issues with no effect on pressure throughout.
