Armstrong Steam and Condensate Group, 816 Maple St., Three Rivers, MI 49093 – USA Phone: (269) 273-1415 Fax: (269) 278-6555armstronginternational.comST-7

The Inverted Bucket Steam Trap

Resistance to damage from water hammerOpen bucket or float will not collapse as a result of water hammer.

Wear and corrosion resistanceFree-floating guided lever valve mechanismis “frictionless,” and all wear pointsare heavily reinforced. All working parts are stainless steel. Valve and seat are stainless steel, individually ground and lapped together in matched sets.

Continuous air and CO2 ventingVent in top of bucket provides continuous automatic air and CO2venting with no cooling lag or threat of air binding. Steam passing through vent is less than that required to compensate for radiation losses from the trap so it’s not wasted.

Excellent operation against back pressureSince trap operation is governed by the difference in density of steam and water, back pressure in the return line has no effect on the ability of the trap to open for condensate and close against steam.

Virtually no steam lossSteam does not reach the

water-sealed discharge valve.

Purging actionSnap opening of the valve

creates a momentary pressure drop and turbulencein the unit drained. This breaksup films of condensate and air

and speeds their flow to the trap.

Dependable operationSimple, direct operation with nothing to stick, bind or clog.

Only two moving parts—the valve lever and the bucket.

Freedom from dirt problemsCondensate flow under the bottom edge of the bucket keeps sediment and sludge in suspension until it is discharged with the condensate. Valve orifice opens wide and closes tightly. No buildup of dirt or close

clearances to be affected by scale.

The inverted bucket is the most reliable steam trap operating principleknown. The heart of its simple design is a unique leverage systemthat multiplies the force provided by the bucket to open the valveagainst pressure. Since the bucket is open at the bottom, it resistsdamage from water hammer, and wear points are heavily reinforced forlong life.

The inverted bucket has only two moving parts—the valve leverassembly and the bucket. That means no fixed points, no complicatedlinkages. Nothing to stick, bind or clog.

Energy Efficient Because It’s So Reliable

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Armstrong Steam and Condensate Group, 816 Maple St., Three Rivers, MI 49093 – USA Phone: (269) 273-1415 Fax: (269) 278-6555armstronginternational.com ST-8

Conserves Energy Even in the Presence of WearArmstrong inverted bucket steam traps open and close based onthe difference in density between condensate and steam—theinverted bucket principle. They open and close gently, minimizingwear. This simple fact means that inverted buckets are subject toless wear than some other types of traps.

In fact, as an Armstrong inverted bucket trap wears, its tight sealactually improves. The ball valve and seat of the Armstrong trapprovide essentially line contact—resulting in a tight seal becausethe entire closing force is concentrated on one narrow seating ring.

An Armstrong inverted bucket trap continues to operate efficientlywith use. Gradual wear slightly increases the diameter of the seatand alters the shape and diameter of the ball valve. But, as this occurs,a tight seal is still preserved—the ball merely seats itself deeper.

Corrosion-Resistant PartsThe stainless steel valve and seat of the Armstrong inverted bucketsteam trap are individually ground and lapped together in matchedsets. All other working parts are wear- and corrosion-resistantstainless steel.

Venting of Air and CO2

The Armstrong inverted bucket provides continuous automatic airand CO2 venting with no cooling lag or threat of air binding.

Operation Against Back PressureThe Armstrong inverted bucket has excellent performance against back pressure. It has no adverse effect on inverted bucketoperation other than to reduce its capacity by the low differential.The bucket simply requires less force to pull the valve open andcycle the trap.

Freedom From Dirt ProblemsArmstrong designed its inverted bucket to be virtually free of dirtproblems. The valve and seat are at the top of the trap, far awayfrom the larger particles of dirt, which fall to the bottom. Here theup-and-down action of the bucket pulverizes them. Since the valveof an inverted bucket is either fully closed or open, dirt particlespass freely. And the swift flow of condensate from under the bucket’s edge creates a unique self-scrubbing action that sweeps dirt out of the trap.

Armstrong IB Valve Seating/Ball Valve IB Valve Wear Characteristics

Line Contact—Single Seat

Infinite Number of Center Lines andSeating Circumferences

Armstrong IB ball valve continues to seat itself deeper, providing a tightseal even in the presence of wear.

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Armstrong Steam and Condensate Group, 816 Maple St., Three Rivers, MI 49093 – USA Phone: (269) 273-1415 Fax: (269) 278-6555armstronginternational.com

How to Use the IB Trap Summary Capacity Chart

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This catalog should be utilized as a guide for the installation andoperation of steam trapping equipment by experienced personnel.Selection or installation should always be accompanied by competenttechnical assistance or advice. Armstrong and its local representativesare available for consultation and technical assistance. We encourageyou to contact your Armstrong Representative for complete details.

The summary capacity chart plots actual trap capacity vs. inletpressure on a log-log grid. The trap capacities become straight lineson this grid. The small numbers along the pressure axis identify the subdivisions; for example, between the large 10 and 100, thenumbers 2, 3, 5, and 7 represent 20, 30, 50 and 70 psi.

The summary chart combines many trap families into one chart bypresenting only a portion of the capacity line for each orifice size.For charts that give capacity over a wide range of pressures, seethe specific trap model pages.

Individual capacity charts for various traps are given throughoutthis catalog. Those charts show capacity lines for each orifice, withpressures usually from 1 psi up to the maximum rated pressure ofthat orifice.

To select an inverted bucket steam trap using the summary capacitychart, you must know the condensate load, safety factor, inlet pressureand outlet pressure. Remember, the object is to select a trap thatcan 1) operate at the maximum inlet pressure, and 2) handle thecapacity at the minimum differential pressure. Consider the followingtypical problems.

Example 1. Constant pressure, condensing rate.Given:Maximum inlet pressure . . . . . . . . . . . . . . . . . . . . . . . . . .70 psiNormal operating differential pressure . . . . . . . . . . . . . . . .60 psiRequired capacity = 300 lb/hr condensate load times 3:1 safety factor, or . . . . . . . . . . . . . . . . . . . . . . .900 lb/hr

Enter the chart at the 60 psi line and go up to 900 lb/hr capacity.This is directly on the 5/32'' orifice line for models 211, 811 and 881(and other traps). Now follow this line to the right, to the verticaldrop at 70 psi. This means the orifice will work, in these traps, upto a maximum differential of 70 psi. Assuming a cast iron trap issuitable, the 5/32'' orifice in a Model 211, 811 or 881 trap will meetall the operating requirements.

Example 2. Constant condensing rate but with possible reduced inlet pressure.Given:Maximum inlet pressure . . . . . . . . . . . . . . . . . . . . . . . . .100 psiMinimum inlet pressure . . . . . . . . . . . . . . . . . . . . . . . . . . .40 psiRequired capacity = 400 lb/hr condensate load times 3:1 safety factor, or . . . . . . . . . . . . . . . . . . . . . .1,200 lb/hr

Consider the maximum operating pressure first. Enter the chart atthe 100 psi line and find the first capacity line above 1,200 lb/hr.This is the 5/32'' orifice in a Model 212, 812 or 882, and it has a capacity of 1,800 lb/hr at 100 psi. Now extend this straight line to the left until it intersects the 40 psi pressure line. At 40 psi, reada capacity of 1,300 lb/hr. (You could also refer to the individualcapacity charts for Models 212, 812 or 882.) Assuming cast iron issuitable, this is the desired trap selection to meet the requirementsof opening at the maximum pressure, and also having the neededcapacity at the minimum pressure.

This example points out how the capacity is influenced by the trapsize. Example 1 also used the same orifice size, but in a physicallysmaller trap. In the larger trap the same diameter orifice not onlyhas a higher capacity, it will work at higher pressures.

Example 3. Constant condensing rate but high back pressure.Given: Inlet pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100 psiNormal outlet (back) pressure . . . . . . . . . . . . . . . . . . . . . .50 psiRequired capacity = 1,800 lb/hr condensate loadtimes 3:1 safety factor, or . . . . . . . . . . . . . . . . . . . . . .5,400 lb/hr

Traditional method:Since the differential pressure is only 50 psi, enter the chart at 50 psiand go up to a capacity of 5,400 lb/hr. This is just under the capacitylines for Models 214 and 814. However, the 5/16'' orifice is the largestorifice that will operate at 100 psi inlet pressure. (Remember thatthe back pressure may not always be there!) Extend the capacityline for the 5/16'' orifice to the left, and read a capacity of 4,800 lb/hrat 50 psi. Since this is too low, go up to the 215/815 capacity linesand repeat the process. The selection will end up being a Model 215or 815 with a 3/8'' orifice*.

About this chart ...The Armstrong capacity chart shows continuous discharge capacitiesof Armstrong traps under actual operating conditions, as determinedby many hundreds of tests made over the years. In these tests, hot condensate was used, at or near the steam temperature corresponding to the test pressure. The choking effect of flash steamin the orifice and the back pressure created by this flash steam weretherefore automatically taken into account. The test setups were similarto an actual installation hookup, so that pipe friction in both inlet anddischarge lines was reflected in the results.

* This method is conservative. While it will always select a workabletrap, it may select a larger trap than necessary. Consult ArmstrongApplication Engineering for further information about the effectsof back pressure.

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Differential Pressure, bar

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IB Trap Summary Capacity Chart

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