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Last updateWed, 22 Nov 2017 2pm

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Unique Operating Dynamics of Trunnion-Mounted Ball Valves

Unique Operating Dynamics of Trunnion-Mounted Ball Valves

For a very long time, the idea has exist...

Adopting the IIoT: Are Results Matching the Hype?

Adopting the IIoT: Are Results Matching the Hype?

Many valve, actuator and control manufac...

Where Valves Are Used: Everywhere!

Where Valves Are Used: Everywhere!

Valves can be found just about anywhere ...

Oxygen Cleaning: A Validated Process is Critical for Safety

Oxygen Cleaning: A Validated Process is Critical for Safety

From time to time, we re-publish well-re...

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Industry Headlines

Conference Board Economic Index Rose in October

Tuesday, 21 November 2017  |  Chris Guy

The Conference Board Leading Economic Index (LEI) for the U.S. increased 1.2% in October to 130.4 (2010 = 100), following a 0.1% increase in September...

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Industry Headlines

VanAire Celebrates Manufacturing with ‘Industry After Hours’

4 DAYS AGO
VanAire Celebrates Manufacturing with ‘Industry After Hours’

On Nov. 8, Delta County, MI K-12 students and parents attended Industry After Hours at VanAire to learn more about the high tech, high skilled manufacturing jobs that are available. Over 276 participants were treated to a fun, entertaining and informative event that exceeded expectations and inspired ...

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Emerson Opens Solutions Center in Singapore

7 DAYS AGO

As part of its drive to make Singapore a hub for the delivery of Industrial Internet of Things (IoT) technologies and services for customers across Asia Pacific, Emerson opened a customer-focused Solutions Center at the regional headquarters of its Automation Solutions business in Singapore. To mark...

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Nebraska Approves Keystone XL Pipeline Route

4 DAYS AGO

By a vote of 3-2, the Nebraska Public Service Commission approved an order giving TransCanada the go ahead to build the Keystone XL Pipeline utilizing the proposed Mainline Alternative Route. This is one of three proposed routes included in the application filed by TransCanada Keystone Pipeline. L.P...

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Energy Outlook Shows a World in Transformation

10 DAYS AGO

The resurgence in oil and gas production from the United States, deep declines in the cost of renewables and growing electrification are changing the face of the global energy system and upending traditional ways of meeting energy demand, according to the World Energy Outlook 2017 . A cleaner and more...

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Conference Board Economic Index Rose in October

3 DAYS AGO

The Conference Board Leading Economic Index (LEI) for the U.S. increased 1.2% in October to 130.4 (2010 = 100), following a 0.1% increase in September, and a 0.4% increase in August.

“The U.S. LEI increased sharply in October, as the impact of the hurricanes dissipated,” said Ataman Ozyildi...

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U.S. Industrial Output Up 0.9% in October

7 DAYS AGO

Industrial production rose 0.9% in October, and manufacturing increased 1.3%. The index for utilities rose 2.0%, but mining output fell 1.3%, as Hurricane Nate caused a sharp but short-lived decline in oil and gas drilling and extraction. Even so, industrial activity was boosted in October by a return...

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The Well-Functioning Steam Trap

vmwnt09 beyond valves 1Ultrasonic instruments are used to test a thermodynamic steam trapSteam traps are the most important link between the steam and condensate system. Malfunctioning steam traps can waste tremendous amounts of money. Here is an example: A single inverted bucket steam trap (with a one-eighth-inch orifice) blowing-thru in a 150 psi, where the steam cost is $11.00 per 1,000 lbs. of steam produced, will waste 62.49 lbs. of steam per hour and cost approximately $6,022 in fuel losses per year.

 

Steam Traps Defined

For those who are not familiar with the steam trap, it is an automatic valve that, when operating properly, opens to purge a steam system of condensate and closes with the presence of steam.

There are three types of steam traps:

  • Density operated, which includes the inverted-bucket (IB) and the float and thermostatic (FT) types
  • Thermostatic (TH), specifically, the balance-pressure thermostatic (BPT) type
  • Thermodynamic (TD), either the disc or impulse type

Trap Characteristics

vmwnt09 beyond valves 2An inverted bucket steam trapFloat and thermostatic traps consist of a ball float and a thermostatic bellows element. As condensate flows through the body, the float rises or falls, opening the valve according to the flow rate. The thermostatic element discharges air from the steam lines. They are good in heavy and light loads and on high and low pressure, but are not recommended where water-hammer is a possibility.

When these traps fail, they usually fail closed. However, the ball float may become damaged and sink down, failing in the open position. The thermostatic element may also fail and cause a fail-open condition.

Thermostatic traps have, as the main operating element, a metallic corrugated bellows that is filled with an alcohol mixture that has a boiling point lower than that of water. The bellows will contract when in contact with condensate and expand when steam is present. Should a heavy condensate load occur, such as in start-up, the bellows will remain in a contracted state, allowing condensate to flow continuously. As steam builds up, the bellows will close. Therefore, there will be moments when this trap will act as a “continuous flow” type while at other times it will act intermittently as it opens and closes to condensate and steam, or it may remain totally closed.

These traps adjust automatically to variations of steam pressure but may be damaged in the presence of water-hammer. They can fail open should the bellows become damaged or due to particulates in the valve hole that will prevent adequate closing. Sometimes the trap becomes plugged and will fail closed.

Inverted bucket traps have a “bucket” that rises or falls as steam and/or condensate enters the trap body. When steam is in the body, the bucket rises, closing a valve. As condensate enters, the bucket sinks down, opening a valve and allowing the condensate to drain.

Inverted bucket traps are ideally suited for water-hammer conditions but may be subject to freezing in low temperature climates if not insulated. When an inverted bucket trap fails, it fails open due to the bucket losing its prime and sinking, or from impurities in the system that may prevent the valve from closing.

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