Inverted Bucket Steam Traps - The How, What, & Why

The What, Why, & How Of The Inverted Bucket Steam Trap

After a brief hiatus, we are going to focus on that quick & easy solution for the industrial customer, the inverted bucket steam trap. Hearing some manufacturers talk about the inverted bucket steam trap, you would think it was the greatest invention the HVAC industry ever offered for condensate recovery (*cough, Armstrong International). As with most things, the truth lies somewhere behind all of the fancy marketing.

First let’s discuss what it is, the inverted bucket steam trap is a mechanical steam trap designed to trap steam and evacuate air and other non-condensable gases from steam piping while evacuating condensate. It achieves this primarily by means of (drumroll please) an inverted bucket! The bucket is attached to a linkage assembly allowing it to freely rise and fill inside the steam trap housing. This linkage assembly also contains a hardened valve that connects to the trap’s discharge seat, or orifice. When the bucket rises as condensate is being discharged and steam is re-entering the trap the valve plugs the seat to prevent steam from exiting the trap orifice. As this steam condenses and the bucket loses buoyancy the valve dislodges from the trap orifice and the bucket falls. Pictures are worth a thousand words, check out this great video from Spirax Sarco on the operation of an inverted bucket steam trap, https://youtu.be/nn1pfrjRXP4.

Now that we know the what and some of the how, let’s discuss the why. Like, why would you choose an inverted bucket steam trap. As you may have gathered from the above description (and seen in the video) an inverted bucket steam trap works A LOT! Now, unlike what some manufacturers (*Ahem…Armstrong International) will tell you, the inverted bucket steam trap is not a great fit when you have air and non-condensable gases. True, these will be evacuated from the trap out of the orifice but they will do so only when the trap is discharging condensate. And, this will be done through the same chamber. So, when you have air and non-condensable gases in greater volume like say in a low pressure steam system an inverted bucket is not the best choice. Armstrong International, Hoffman Specialty, Spirax Sarco, and Watson McDaniel all offer some form of air vent for additional removal of air. We at Athena Supply though recommend the float & thermostatic steam trap be considered instead. But, when you have steady pressure and steady steam load the inverted bucket is a great economical solution to remove high pressure condensate. Some manufacturers, and here is where we show Armstrong International some love along with Watson McDaniel, even offer an internal check valve as an option for your inverted bucket steam trap which helps when draining high pressure condensate into a line that is above the trap or into a low pressure line. 

So there you have it. The not so brief over as to the how and why for an inverted bucket steam trap. Next up, our favorite mechanical steam trap the float & thermostatic (F&T) steam trap. And we promise to not take so long the next time around. Don’t forget, all of these traps and more can be found on Athena Supply!