Venturi steam trap - the manufacturers' comments

The independent Energy Technology Savings Unit study on the GEM venturi steam trap shows 19% savings on fuel and more. Here are Gardner Energy Management's comments on the Study.

The independent Energy Technology Savings Unit (ETSU) study on the GEM venturi steam trap shows 19% savings on fuel, 19% reduction in carbon dioxide and nitrogen oxides emissions, low maintenance and no major operational problems.

Here are Gardner Energy Management's comments on the Study.

This study proves that by converting to GEM venturi steam traps, Withington Hospital Laundry realised a permanent steam saving of 19% with no water hammer and no loss of performance.

Although it also showed reduced maintenance requirements, this study fails to include any associated maintenance cost savings and yet adds an estimated cost for cleaning supposed blockages.

The installation cost is inexplicably high.

A payback period of just over 2 years should be taken as highly conservative.

The study concludes that, depending on the condition of existing traps, economic analysis favours continually testing and replacing faulty mechanical traps.

Notwithstanding, Withington Hospital chose to install GEM traps because constant trap testing and replacement failed to control the pluming steam vent and high steam consumption.

The title of this study emphasises one of the main benefits of GEM venturi steam traps: low maintenance.

UK manufacturers are cutting maintenance costs and staff; the consequences are ever-increasing steam loss and escalating fuel bills as mechanical steam traps fail open.

Before the recent advent of the GEM trap, management had two stark options: minimal maintenance and watch the steam plume from the condensate receiver rise along with the fuel, water and chemical treatment costs, or regularly testing, repair and replacement of faulty mechanical traps.

Both were expensive options.

This study shows that the GEM trap is a third and inexpensive option.

After wholesale replacement of mechanical traps at a large hospital laundry, not one operational problem was reported in a full year of monitoring.

Before switching to GEM traps, Withington Hospital faced ever larger steam losses and a condensate receiver bursting at the seams with live steam.

It spent thousands of pounds replacing mechanical traps.

The effect was short-lived, however; the steam plume would soon return.

When the receiver was blown apart by live steam leaking through traps, a raw water dousing system was added to 'put out' the plume, attempting to treat symptoms rather than causes.

Finally Withington Hospital opted for total conversion to GEM traps.

ETSU's photographs of the receiver vent before and after speak for themselves.

The study states that "the replacement of traps on the main laundry equipment resulted in an immediate and dramatic reduction in the steam plume".

Prior to the installation of GEMs, a steam meter in the condense receiver vent showed that well over half a tonne of steam was lost to atmosphere every hour.

After installation, fuel burnt in the boilers was permanently reduced by nearly half a megawatt - the equivalent of 463 one-kW electric bar heaters.

This equates to cutting emissions of carbon dioxide by 237 tonnes and nitrogen oxides by 239 tonnes each year.

And John Tucker, the Hospital's Estate Manager, states in the report that the introduction of GEM traps "resulted in energy savings worth over ?10,000/year." Although the report confirms that GEM traps reduced maintenance requirements, and refers to surveys and fire-fighting maintenance required when the original traps were in place, there is no mention of maintenance savings due to GEM traps.

On the contrary, the report actually adds an estimate of costs for cleaning GEM traps that may block, even though they did not block during the year of monitoring! It also added ?5,000 for installation and supervision, although the traps were installed by in-house maintenance staff at little or no cost to the Hospital.

A contractor's normal fitting charge is approximately ?15 per trap, and even at double this cost the installation bill would not have exceeded ?2,500.

If the substantial maintenance savings are added and account is taken of the doubling of fuel prices since 1998, payback is well below 2 years.

In stark contrast to the prophets of doom, the report states that "there have been no problems due to water hammer, under-performance or steam leakage." And although before the study there was a "perceived inability to effectively drain condense under start-up conditions", the study confirms the opposite: "there were no such problems at the laundry where the steam is isolated and restarted daily".

When mechanical traps jam shut, typical results are wet steam, loss of heat output coupled with waterhammer and, all too often, plant shut down to repair traps.

The study also shows that live steam loss through mechanical traps failed open pressurises condensate systems.

Over half an atmosphere was recorded in the receiver prior to installation of GEM traps, and this was reducing the capacity of all traps and heat output of equipment in the system.

Hardly surprising that a recent independent GEM trap customer survey found that reliability, not energy savings, is top of customers' wish lists.

As laundry equipment has no control valves, it presents the biggest challenge to GEM traps.

They are constantly subjected to full steam pressure and widely varying condensate loads, as equipment is switched on and off.

The study shows that, even under wide variation from full load to minimal standing loads, GEM traps trapped steam effectively and made a permanent 19% steam saving.

The report concludes that "Fixed Orifice Condense Discharge Traps [or GEM traps] should be considered where new steam systems are being installed or in existing systems where steam trap maintenance or reliability is a problem." Maintenance and reliability are continual headaches to steam users.

Typically, Withington Hospital had "continual pressures on the maintenance budget and we were not allowed the luxury of a full planned maintenance system".

Today who doesn't have similar pressures translating into pressures in condensate returns and receiver vents? The way to reduce these pressures now seems obvious.

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