GEM traps come out on top in University trials

It was decided that a variety of steam traps would be utilised in the research including buckets, floats, thermostatic and thermodynamic valve arrangements. Only new traps were used even though it had been previously noted that the performance of mechanical and thermostatic traps diminishes over time as components wear and progressively fail.

A glass constructed ‘climbing film evaporator’ test rig was used as it enabled the flow of steam and condensate to be monitored visually. The rig was designed to work like a normal heat exchanger but had the advantage of enabling heat outputs, and therefore condensate loads, to be altered by regulating the flow of evaporative liquid on the secondary side of the exchanger. This changed the liquid level, and therefore the heat transfer area of the exchanger, without changing steam pressure.

It was decided that the performance analysis would be carried out under maximum steam pressure, utilising a full range of condensate flows, to fully test the traps. However, most industrial variable load applications are fitted with control valves so as the heat loads vary, the steam pressure will be regulated. Therefore at low loads there is less condensate produced and less steam pressure exerted on the trap.

Tests were performed on each trap at a constant pressure of 54 psig (3.7bar) and varying flows from ‘no flow’ to 20 kg/hr. ‘Bucket tests’ were conducted according to the European Standard to measure the live steam loss through traps at five various condensate load conditions expressed as the level of liquid in the evaporative column in the rig.

The results proved that the GEM venturi steam trap is significantly more efficient over varying loads than all other types of traps with the free floating float trap and the more conventional float trap the least efficient with losses averaging over 1.5 kg/hr. The TD thermodynamic and ‘MK’ thermostatic traps were slightly more efficient but all traps were less efficient than the GEM trap. The BPT balanced pressure thermostatic traps were significantly more efficient than any other types of trap at high condensate loads but the GEM was found to be significantly more efficient over varying loads.

In addition the tests also proved, unequivocally, that the GEM trap is more efficient than mechanical traps, disproving previous perceptions that orifice venture traps are inefficient at low load conditions when there is little condensate present to hold back the steam.

Commenting Peter Bennett, Sales & Marketing Director of GEM said: “This research, carried out under the most stringent conditions, has underlined the superiority of the GEM trap. In addition as GEM traps have no moving parts to fail or wear out it obviates the need for continual trap testing, repair and replacement”.