First for Steam Solutions


Energy losses in Steam Traps

Posted by Diana Lymar on Sep 4, 2018 2:00:00 PM


A large amount has been written about this subject, much of which has been inaccurate or deliberately misleading in order to make the case for using various manufacturers' traps.
An argument is made in favour of replacing one type of trap with another and claiming a steam saving which may be real or imaginary. The truth is that replacing any group of traps with new ones will inevitably reduce steam consumption because any leaking traps are thereby eliminated.
This says nothing about the old or new traps.
In other cases, tests have been carried out to establish 'steam wastage'. Some tests are carried out under unrealistic no-load conditions and attempt to overvalue and confuse the amount of energy lost through the trap. Energy loss from the trap due to radiation, which will also increase condensate load, is conveniently ignored. However, these losses will occur at all times and are directly related to the size and shape of the body.
Steam trap users are often confused by subjective information which is intended primarily to create interest in a product. It is therefore worth going back to objective principles and considering the inherent energy requirements of the main types.

Thermostatic steam traps

Under normal operating conditions, the thermostatic trap holds back condensate until it has cooled to a certain temperature. Steam does not reach the main valve so there is no apparent steam wastage.
However, waterlogging of plant can lead to reduced output. Operating times may be extended or additional heaters or heating surfaces may be required. More steam may be required although this will not appear as an energy requirement attributable to the steam trap.
In some cases a cooling leg may be incorporated so that the steam space is kept clear of condensate. Energy is thereby lost due to radiation from the cooling leg and from the trap body.
This in itself creates an additional condensate load, but there is no passage of live steam through the trap.
The situation can change under no-load conditions. Heat loss from the trap body cools the condensate surrounding the element which then opens. The minimal amount of condensate involved is discharged and is then replaced by steam. However, hysteresis means that the element has yet to respond and live steam is lost. Laboratory tests indicate typical losses up to 0.5 kg/ h.
Ironically, under cold outdoor conditions there will be increased heat loss from the trap and steam loss through the trap is less likely. Any attempt to lag a thermostatic trap will result in a serious delay in the opening of the trap. Severe waterlogging will result and hence lagging is not recommend for thermostatic traps.

Mechanical steam traps

The float-thermostatic trap is another example where the valve and seat are normally flooded and there is no steam loss through the trap. Conversely, the float-thermostatic trap is relatively large in size, and there may be a noticeable loss from the trap caused by radiation. Mention should be made of the thermostatic air vent fitted in this type of trap. This will be situated in the steam spaceabove the  water level in the trap. Once initial air has been cleared this will normally remain tight shut and there will be no loss from this source.
The float-thermostatic trap can be lagged to reduce heat losses and this will not affect its operation.
Lagging is normally recommended on outdoor applications to minimise the danger of damage due to freezing when steam might be turned off.
The inverted bucket trap has surprisingly little in common with the float type trap. The trap closes when steam enters and bubbles through into the bucket to make it buoyant. It will not open until the steam has been dissipated.
This will occur as the steam leaks away through the hole in the bucket which serves as an air vent. The steam will collect in the top of the trap itself and when the main valve opens, this steam is vented.
Laboratory tests again indicate losses of around 0.5 kg/ h for ½” traps under these low loadconditions. However, there is additional radiation loss from the body, which can be quite large. 
Lagging is sometimes recommended but the heat loss and its resulting condensate will be much the same as an equivalent float type trap. 

Thermodynamic steam traps

This type of trap has attracted most attention under the heading of steam wastage.
The operation depends on condensate approaching steam temperature, producing flash steam
at the orifice and causing the trap to close. It does this with condensate on the upstream side and again the flooded valve means that there can be no loss through the trap. However the trap will open periodically as heat is lost from the cap.
Under no-load conditions, i.e. when condensate is being produced only by heat loss from the upstream pipeline, the condensate on the upstream side may exhaust and the trap will then require a small amount of live steam to cause it to close. Much will depend on ambient conditions but the loss will generally be around 0.5 kg/ h and this could be doubled in severe weather. Conversely, such losses can be halved by simply fitting an insulating cover over the top cap.
It is important to remember that these losses disappear as the condensate load increases while the radiation losses from the trap are minimal due to its small size. Independent tests have shown that radiation losses are not more than 0.25 kg/ h which is at least a quarter of that experienced by equal sized inverted bucket traps.
Mention should be made of misleading figures quoted by some sources. These have their origins in tests carried out simultaneously on a large number of thermodynamic traps. Some tests were carried out at minus 45°C with the cumulative steam loss being measured. The effect of testing at unusually low temperatures and under no-load conditions was to produce an accelerated life test. The loss through a small number of defects averages out to produce a curve showing losses increasing with time. As already indicated, the thermodynamic trap has the great simplicity in that it either works correctly or fails. To suggest a varying loss is totally misleading and fundamentally flawed.


Quantifying the energy requirements of steam traps is not easy. Energy can be lost through the trap but this may depend on load. Energy will be lost from the trap due to radiation but this can be reduced considerably by lagging.
Table 11.15.1 summarises the energy requirements of a variety of ½" traps at 5 bar g. Clearly traps vary in size and performance so the figures must serve as a guide only.

The purpose of the given table  is not to establish the fact that one type of trap is marginally more efficient than another. It is simply to make the point that steam traps use a minimal amount of energy. Losses only become significant when traps are defective. The important thing therefore is to combine selection, checking and maintenance to achieve reliability. Properly done, costs and steam wastage will be minimised.
Read More

Topics: Steam

How to choose safety valve, which suits your needs?

Posted by Diana Lymar on Jul 10, 2018 2:01:00 PM

As there is such a wide range of safety valves, there is no difficulty in selecting a safety valve that meets the specific requirements of a given application. Once a suitable type has been selected, it is imperative that the correct relieving pressure and discharge capacity are established, and a suitably sized valve and set pressure is specified.

The selection of a specific type of safety valve is governed by several factors:

Read More

Topics: Valve regulations

Concerns raised over high limit control valve maintenance

Posted by Diana Lymar on Jun 26, 2018 2:04:00 PM

High limit control valves are widely used in commercial buildings such as hospitals, schools, and offices, but could the way you maintain yours risk breaching health and safety guidelines? Dave Bell, our Field Services Manager, explains:

Read More

Topics: Valve regulations

Steam system efficiency = Savings

Posted by Diana Lymar on Jun 18, 2018 2:01:00 PM

With the 2020 emissions target looming, the need to reduce our energy use has never been greater. Industry undoubtedly has an important part to play and through sufficient expertise, and a few small changes, you can make a big difference to your plant’s carbon footprint. Steam is widely used across a number of industries and applications. Take for example the food and beverage sector, in which steam plays a vital role for a variety of processes, including blanching, bottle washing, peeling, canning and cooking. The potential for such industries to make a real difference to our collective carbon performance is therefore huge. Crucially, these improvements don’t require a major overhaul as you can make simple changes to equipment you already have in the plant. To get you started we’re sharing our top three measures which can significantly reduce your energy consumption and help you achieve impressive savings. Steam trap facts Given the current economic climate, you’ll be reassured to know that optimising the efficiency of your plant’s steam system could be easier than expected. Steam traps, for example, are the most important link in the condensate loop and can help to lower energy consumption and increase productivity. Effective steam trapping is therefore an essential process that can help you operate more sustainably.

Read More

Topics: Steam Trapping

Could your heat transfer technology be failing your business?

Posted by Diana Lymar on May 29, 2018 2:02:00 PM

Effective energy transfer may be a basic prerequisite for the success of your industrial process, but heat exchanger failure is leaving engineers frustrated by unplanned downtime, increased maintenance costs and spiralling production costs. Amidst this frustration, there is a modern technology capable of making heat transfer equipment work much more effectively for your business.

Read More

The efficient work of separators: look inside

Posted by Diana Lymar on Apr 20, 2018 2:00:00 PM

Wet steam can cause a number of problems in the system including a reduction in heat transfer efficiency, increased erosion and possible corrosion. Entrained water flowing through control valves, flowmeters and rotating or reciprocating equipment significantly affects performance and can eventually lead to an inefficient system and plant downtime. The primary purpose of a separator is to remove water which may be suspended in the steam supply. Installing separators at key points around the system helps keep the steam dry. This allows vital equipment to operate as productively as possible and helps to maintain optimum conditions throughout the entire system.


Read More

Topics: Separators

See how intelligent trap monitoring can help you adopt a predictive maintenance model

Posted by Diana Lymar on Apr 3, 2018 2:05:00 PM

Currently many manufacturers are restricted by a reactive maintenance model (fix when you realise its broken) leading to unpredictable expenses and inefficient use of labour and resources. Intelligent monitoring allows users to move to a predictive maintenance model through data interpretation helping to not only highlight traps that are failed but that are failing. Monitoring the performance of steam traps over a period of time enables the user to map deterioration and schedule future maintenance requirements with advanced warning and ample preparation. A preventive maintenance model allows the user to optimise efficiency, maintain performance and minimise risk within their steam system.

Read More

Topics: Monitoring


Posted by Diana Lymar on Mar 20, 2018 1:00:00 PM

Recovering energy from hot and dirty exhaust gases is now possible.

Read More

Why you should monitor your steam traps more closely

Posted by Diana Lymar on Feb 20, 2018 1:02:00 PM

Steam leaks are costly in both a financial and environmental sense and therefore need prompt attention to ensure your steam system is working at its optimum efficiency with a minimum impact on the environment. A steam trap can be classified as failed if it’s leaking above acceptable levels or has become blocked or failed closed.

Read More

Topics: Steam Trapping

Five key factors that will impact the quality of your steam

Posted by Diana Lymar on Jan 23, 2018 1:03:00 PM


Read More

Subscribe to Email Updates

Recent Posts

Speak to our steam experts

We have helped hundreds of steam users around the world to save energy and optimize their system.

Contact Us