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Everything listed under: Test Your Knowledge

  • Test Your Knowledge: Which Device Is It?

    Which of the following helps minimize water hammer, helps drains condensate, and minimizes temperature swings?

    1. Inverted Bucket Steam Trap
    2. Vacuum Breaker
    3. Fluid Air Coil
    4. Mechanical Condensate Pump
    5. Pilot Operated Regulating Valve

    And the answer is...

    2. Vacuum Breaker

    A Vacuum Breaker is a simple, reliable device that allows air to enter a steam piping system when a vacuum is induced. When a steam system shuts down, the remaining steam condenses into water, which takes up a much smaller volume than the original steam. This creates a vacuum, which can lead to water hammer and tube damage if not relieved of in a timely way. 

    Check out this video which shows the proper use of a vacuum breaker in a steam system.

    Here are our top 4 reasons for including a vacuum breaker in your system:

    1. It helps allow for complete condensate drainage under all operating conditions: on/off or modulating applications. 
    2. It helps minimize water hammer. 
    3. It helps minimize temperature swings and uneven temperatures. 
    4. It helps minimize product waste.

    All heat transfer components, whether shell-and-tube exchanger, plate-and-frame exchanger, air heating coil or any other device, require vacuum breakers. As the video shows, because the condensate piping after our coil is clear glass, you can watch condensate backing up into the coil without a vacuum breaker.  Once the vacuum breaker is allowed to operate, the coil can remain free of condensate under all operating conditions, which eliminates many issues that can shorten equipment service life and/or cause operation problems.

    The footage for that video was taken in our Steam Training Room located in Minnetonka, Minnesota, where we have regular training classes.  We utilize a steam boiler, glass piping, and functional glass-bodied steam traps to describe and demonstrate a variety of steam basics and advanced concepts in the 4 main areas of a steam system: Generation, Distribution, Utilization, and Condensate Return.

    Contact us for more information on the proper use of vacuum breakers or sign up for our Steam Energy Conservation seminars to learn more. 


  • Test Your Knowledge: Emergency Low Boiler Water Level

    You find the boiler water-level gauge glass to be empty and the burner firing. What is your course of action? (Assuming the gauge glass to be clear & good working order)

    A. Blow down the gauge glass to determine where the water level is

    B. Increase the feedwater supply to maintain the water level

    C. Start the emergency feedwater injector to restore normal water level

    D. Shut down the boiler to minimize damage to the boiler tubes

    And the answer is...

    Answer: D. Shut down the boiler
    Normally a boiler is provided with two independent sensors for emergency low water level burner cut-outs. So this would never happen. However, if it does, don't take any chances! Shut off the burners immediately!

    Before you start raising the level in the boiler you have to find out if any part of the furnace walls has been overheated. If you raise the level over a glowing steel-wall then the boiler might produce more steam than the safety valves can handle and a nasty explosion would be the result.

  • Test Your Knowledge: Energy Assessments

    According to the U.S. Department of Energy’s Industrial Technologies Program, plants that do energy assessments of their steam systems typically uncover opportunities for reducing energy and cost savings range from _____________ per year?

    1. 3%-7%
    2. 5%-10%
    3. 10%-15%
    4. 12%-18%
    5. 15%-20%

    And the answer is...

    3. 10%-15%

    Steam systems account for about 30% of the total energy used in industrial applications for product output. These systems can be indispensable in delivering the energy needed for process heating, pressure control, mechanical drives, separation of components, and production of hot water for process reactions.

    As energy costs continue to rise, industrial plants need effective ways to reduce the amount of energy consumed by their steam systems. Industrial steam systems can include generation, distribution, end use, and recovery components, as shown in the diagram. End-use equipment includes heat exchangers, turbines, fractionating towers, strippers, and chemical reaction vessels. Steam systems can also feature superheaters, combustion air preheaters, feedwater economizers, and blowdown heat exchangers to boost system efficiency. 

    According to the U.S. Department of Energy’s Industrial Technologies Program, making steam systems more efficient throughout industry could reduce annual plant energy costs by several billion dollars and environmental emissions by millions of metric tons. Typically, plants that assess their steam systems uncover potential steam system energy use and cost savings that range from 10% to 15% per year.

    Facts & Figures

    • About one-third of the nation’s total energy use is consumed in U.S. industrial facilities; nearly one-ninth is used by steam systems.
    • Industry consumes more than 40% of the nation’s total use of natural gas.
    • Even plants with energy management programs can often save 10% to 15% more using best practices to increase their energy efficiency.
    • System improvements can often reduce the energy costs of a typical industrial steam system by 10% to15%.


    • Energy efficiency improvements can reduce utility bills and improve your plant’s bottom line.
    • Many improvements require little or no extra investment, are easy to implement, and have payback times of less than a year.
    • Strategies that increase energy efficiency often reduce operating and maintenance costs, minimize waste, and enhance production.
    • Energy efficiency helps to reduce negative impacts on the environment and can enhance corporate community relations programs.

    Click to download the entire report from the U.S. Department of Energy and see a list of typical ways to increase steam system efficiency. For more information on doing a Utility Systems Study within your plant, contact the team at Campbell-Sevey


  • Test Your Knowledge: The Three Element System

    The three element system for controlling the boiler drum level considers which three parameters?

    1. Feed Water Flow, Fuel Flow, Liquid Level
    2. Feed Water Flow, Combustion Air Flow, Liquid Level
    3. Feed Water Flow, Fuel Flow, Steam Flow
    4. Feed Water Flow, Steam Flow, Liquid Level

    And the answer is...

    4. The "three element control" in boilers stands for the three control element, each measuring an individual process variables;

    • Flowrate of boiler feed water
    • Flowrate of steam leaving the boiler
    • Liquid level inside steam drum

    For any boiler, controlling the liquid level at the optimum range is the highest priority. It needs to be high enough to ensure that water is present in every steam generating tube, yet low enough to provide sufficient space for steam above the liquid. 

    For boilers operating at low pressure, it is relatively inexpensive to have a large steam drum in which the liquid level moves very slowly. But for boilers operating at medium or high pressure, larger steam drums are more expensive, so in most cases these steam drums are small. This means that liquid levels can fluctuate very quickly. To protect against this fluctuation, the three element control is typically used.

    Why 3 elements instead of 2 elements?

    Suppose we have a 2 element control which directly controls the flowrate of boiler feed water (by opening/closing control valve) based on the liquid level in the steam drum. If the level decreases, the control valve opening will increase to increase the flowrate of feed water. But lets say at the same time the steam requirement changes whichl fluctuates the steam drum pressure. 

    For instance, if the liquid level decrease in the steam drum that forces the control valve to increase the flowrate (suppose 50% to 70%) so that it will balance the system. At a result, steam consumption decreases and pressure increases in the steam drum. In this scenario the control valve opening will still remain 70% because it will not consider the decrease in steam flowrate. Therefore the 70% opening of the control valve will give the same flowrate it was getting before with the 50% opening. In this case, the 2 element control will not work.

    To avoid theissue, the 3 element control system is installed (the third element measures the steam flow rate). Now if the level in the steam drum fluctuates at the same time as the steam requirement, the steam flowrate signal will go into the flow controller of the boiler feed water and adjust the opening of control valve accordingly to get the desired flow of water inside the steam drum.

  • Test Your Knowledge: Steam Traps

    Above are five different types of steam traps. Which one is the Inverted Bucket Steam Trap?

    • A
    • B
    • C
    • D
    • E

    And the answer is... 

    D. The Inverted Bucket Steam Trap

    The inverted submerged bucket steam trap is a mechanical trap that operates on the difference in density between steam and water. Steam entering the inverted submerged bucket causes the bucket to float and close the discharge valve. Condensate entering the trap changes the bucket to a weight that sinks and opens the trap valve to discharge the condensate. Unlike other mechanical traps, the inverted bucket also vents air and carbon dioxide continuously at steam temperature.

    Here are descriptions of the other steam traps shown:

    A. The Control Disc Steam Trap

    The controlled disc steam trap is a time-delayed device that operates on the velocity principle. It contains only one moving part, the disc itself. Because it is very lightweight and compact, the CD trap meets the needs of many applications where space is limited. In addition to the disc trap’s simplicity and small size, it also offers advantages such as resistance to hydraulic shock, the complete discharge of all condensate when open and intermittent operation for a steady purging action.

    B. The Float and Thermostatic Steam Trap

    The float and thermostatic trap is a mechanical trap that operates on both density and temperature principles. The float valve operates on the density principle: A lever connects the ball float to the valve and seat. Once condensate reaches a certain level in the trap the float rises, opening the orifice and draining condensate. 

    C. The Bimetallic Steam Trap

    Bimetallic steam traps have the ability to handle large start-up loads. As the trap increases in temperature, its stacked nickel-chrome bimetallic elements start to expand, allowing for tight shutoff as steam reaches the trap, thus preventing steam loss. In addition to its light weight and compact size, it offers resistance to water hammer.

    E. The Thermostatic Steam Trap

    Thermostatic steam traps operate on the difference in temperature between steam and cooled condensate and air. Steam increases the pressure inside the thermostatic element, causing the trap to close. As condensate and non-condensable gases back up in the cooling leg, the temperature begins to drop, and the thermostatic element contracts and opens the valve. The amount of condensate backed up ahead of the trap depends on the load conditions, steam pressure and size of the piping. It is important to note that an accumulation of non-condensable gases can occur behind the condensate backup.

    For complete descriptions of each trap as well as instructions on how to trap, download Armstrong's Steam Conservation Guidelines for Condensate Drainage

  • Test Your Knowledge: How to Solve Equipment Stall

    Stall is easily defined as a condition in which heat transfer equipment is unable to drain condensate and becomes flooded due to insufficient system pressure. It happens for a variety of reasons, but it always comes back the fact that there is not always enough system pressure to return the condensate.

    Over the years there have been a variety of “solutions” that would all alleviate the stall scenario, but which of the following solutions is considered the best?

    1. Installation of a Vacuum Breaker
    2. Installation of a Positive Pressure System
    3. Installation of a Safety Drain
    4. Installation of a Pump Trap in a Closed System

    And the answer is...

    4. Installation of a Pump Trap in a Closed System

    The benefits of using a pump trap in a closed system to solve the problem of “stall” can provide multiple benefits that reduce maintenance, improve performance, increase equipment life, and provide significant cost savings in installation and operation. Here is an outline from Armstrong on understanding and solving equipment stall in fluid handling. 

    Armstrong Fluid Handling Understanding and Solving Equipment Stall

    Everyone has heard of it, everyone has seen or experienced it. So why is there so much mystery surrounding equipment “stall”. Stall can most easily be defined as a condition in which heat transfer equipment is unable to drain condensate and becomes flooded due to insufficient system pressure.

    What causes stall?

    Stall occurs primarily in heat transfer equipment where the steam pressure is modulated to obtain a desired output (i.e. product temperature). The pressure range of any such equipment ( coils, shell & tube, etc.…) can be segmented into two (2) distinct operational modes: Operating and Stall

    Operating: In the upper section of the pressure range the operating pressure (OP) of the equipment is greater than the back pressure (BP) present at the discharge of the steam trap. Therefore a positive pressure differential across the trap exists allowing for condensate to flow from the equipment to the condensate return line.

    Stall: In the lower section of the pressure range the operating pressure (OP) of the equipment is less than or equal to the back pressure (BP) present at the discharge of the steam trap. Therefore a negative or no pressure differential exists, this does not allow condensate to be discharged to the return line and the condensate begins to collect and flood the equipment.

    Effects of “stall”

    In a stall condition condensate accumulates within the equipment. When equipment becomes flooded by stalled condensate a variety of problems ranging from minor to catastrophic failure will occur. 

    Problems associated with stall: 

    • Inadequate condensate drainage
    • Waterhammer (Thermal shock)
    • Frozen coils
    • Corrosion due to cool condensate and the formation of Carbonic acid
    • Poor temperature control
    • Short equipment life
    • Control valve hunting (system cycling)
    • Reduction in heat transfer capacity

    Factors contributing to “stall”

    Stall happens for a variety of reasons, but it always comes back the fact that there is not always enough system pressure to return the condensate. The lack of sufficient pressure in the equipment may be caused by anyone of the following:

    • Oversized equipment (excessive surface area)
    • Overly conservative fouling factors
    • Back pressure at equipment discharge due to elevation or pressure in the line
    • Modulating control
    • Equipment operating at lower pressures due to light load demands
    • Vacuum

    Many types of heat transfer equipment are susceptible to stall because they are designed with excessive safety factors built into the design. In attempting to provide an extremely robust heat exchanger, equipment manufactures and engineers often “over design” equipment which often lends itself to a stall scenario.


    The problems of equipment stall are well known and well documented. Over the years there has been a variety of so called “solutions” that would all alleviate the stall scenario.

    > Installation of a vacuum breaker:


    To relieve a vacuum within equipment allowing for condensate drainage.


    1. This practice will only help if the condensate is gravity drain to atmosphere, any pressure present at the discharge of the trap will not allow condensate drainage.
    2. Allows undesirable air into the system.
    3. Vacuum breakers often fail due to a poorly chosen location downstream of the equipment causing a build-up of scale/sediment impeding the operation. Such a location may also allow the hydrostatic pressure of a vertical water column to keep the vacuum breaker closed in a small vacuum.
    4. Loss of valuable flash steam

    > Installation of a safety drain:


    The use of a second steam trap located above the primary trap which discharges condensate to drain when the system goes into a stall condition.


    A significant amount of condensate/flash steam and valuable BTU’s are lost down the drain when the system is in stall. Stall load may as high as 90% or more of the design load, therefore 90% of the condensate coming from the equipment goes down the drain

    > Installation of a positive pressure system:


    The use of air or other gas to maintain set pressure to ensure a positive pressure differential across the trap allowing for condensate drainage.


    Injects a significant amount of undesirable air into the equipment. This large amount of air may cause multiple problems:

    1. Air acts as an insulator thereby decreasing the heat transfer capacity of the equipment.
    2. A heavy dependence on air vents to evacuate the air from the equipment.
    3. Air vents may be open a significant amount of time allowing for loss of valuable BTU’s.

    > The Solution: Closed System Pump Trap

    The application of a “closed” system pump trap on your modulating steam equipment can provide the following benefits:

    • Continuous condensate drainage, even in a vacuum
    • Eliminates the need for vacuum breakers
    • Saves valuable flash steam from escaping into the atmosphere
    • No need to run expensive vent lines
    • Size pump traps on stall load, resulting in smaller pumps and less cost
    • No rotating seals, cavitation, or NPSH requirements
    • Negligible operating cost
    • Longer equipment life
    • Reduced corrosion
    • Better temperature control
    • Reduced maintenance…….and more

    The Closed Loop Concept

    The closed loop application of a pump trap is based around one basic concept: To equalize the pressure in the heat exchange equipment and the pump trap thereby allowing condensate to drain by gravity to the pump trap.

    The equalization of pressure is accomplished by:

    1. Connecting the vent of the pump trap to the inlet steam side of the equipment or to a condensate receiver upstream of the pump trap.
    2. Placing the steam trap on the outlet side of the pump trap or eliminating the steam trap altogether


    The benefits of using a pump trap in a closed system to solve the problem of “stall” can provide multiple benefits that reduce maintenance, improve performance, increase equipment life, and provide significant cost savings in installation and operation. Applications for applying pump traps in closed systems to eliminate problems with stall exist at almost every facility. 

    To learn more click to download the full Armstrong Fluid Handling Understanding and Solving Equipment Stall paper or contact the team at Campbell-Sevey.

  • Test Your Knowledge: Top 3 Industrial Users of Steam

    Which industries are the top 3 users of steam?

    1. Chemical Processing
    2. Mining
    3. Petroleum Production and Refining
    4. Power Generation
    5. Pulp and Paper
    6. Textile

    The answer is...

    1, 4 and 5

    Chemical Processing – Within the chemical processing industry, steam is applied to a wide array of different applications including: Automation, Dilution, Fractionation, Quenching, Mechanical Drive, and Stripping.

    Power Generation – The power generation industry is heavily reliant on steam power, with the exception of renewable sources. The use of steam condensate reduces water sourcing costs and lessens the environmental impact of power plants.

    Pulp and Paper – Pulp and paper mills require tremendous amounts of water and steam, making the industry the largest steam user aside from power generation. Steam is used in a variety of pulp cooking processes.

  • Test Your Knowledge: Longitudinal and Circumferential Stress

    What is the relationship between longitudinal stress and circumferential stress:

    A. They are the same

    B. Longitudinal stress is twice circumferential stress 

    C. Circumferential stress is twice longitudinal stress

    D. There is no fixed relationship between the two

    And the answer is...

    C. Circumferential stress is twice longitudinal stress

    Internal pressure can be produce by water, gases or others. When a thin – walled cylinder is subjected to internal pressure, three are two mutually stresses:

    • Circumferential or Hoop stress
    • Longitudinal stress

    Circumferential or Hoop Stress: This is the stress which is set up in resisting the bursting effect of the applied internal pressure and can be most conveniently treated by considering the equilibrium of the cylinder. The hoop stress is the force exerted circumferentially (perpendicular both to the axis and to the radius of the object) in both directions on every particle in the cylinder wall.

    The effect of this may split the pipe into two halves. The failure of the pipe in two halves in fact is possible across any plane, which contains diameter and axis of the pipe. Elements resisting this type of failure would be subjected to stress and direction of this stress is along the circumference. 

    Longitudinal Stress: Consider a cyclinder that could have closed ends and contain a fluid under a gauge pressure. Then the walls of the cylinder will have a longitudinal stress as well as a circumferential stress.

    Considering that the pipe ends are closed and pipe is subjected to an internal pressure ‘P’ the pipe may fail. Elements resisting this type of failure would be subjected to stress and direction of this stress is parallel to the longitudinal direction of the pipe. 

    Radial stress: Radial stress can also be a factor in thick-walled pipe. It is stress in directions coplanar with, but perpendicular to, the symmetry axis. The radial stress is equal and opposite to the gauge pressure on the inside surface, and zero on the outside surface.

  • Test Your Knowledge: Back Pressure

    Back pressure within a steam system is cause by ALL of the following EXCEPT which one:

    1. Back pressure from lift - every 2 feet of lift takes 1 psi
    2. Back pressure from flow - pressure drop is caused by flow
    3. Back pressure from equipment - check valves cause back pressure
    4. Back pressure from bad traps - blowing through traps create a huge steam flow through the condensate line
    5. Back pressure from water hammer - the hammer impact causes pressure within the system

    And the answer is...

    5. Back pressure from water hammer. 

    While water hammer is damaging, back pressure is caused by lift, flow, equipment and bad traps. When these are combined:

    • Back pressure from lift plus
    • Back pressure from flow plus
    • Back pressure from equipment plus
    • Back pressure from blowing though steam traps

    Properly sized steam traps can eliminate back pressure. When the team at Campbell-Sevey determines trap sizing we consider the following factors:

    • Modulated or constant steam pressure?
    • What is the maximum condensate load?
    • What is the differential pressure at the trap?

    If you have questions about how to regulate and control back pressure from your steam system, contact the team at Campbell-Sevey


  • Test Your Knowledge: Boiling Point of Water Above Sea Level

    What is the boiling point of water at 2000 feet above sea level?

    1. 218º - The higher the elevation the more heat it takes (3º for every 1000')
    2. 214ºF - It takes a little more heat (1º for every 1000')
    3. 212ºF - The boiling point is the same no matter what the elevation is
    4. 208ºF - It takes less heat the higher you go (-2º for every 1000')
    5. 182ºF - Elevation plays a big difference in boiling point (-15º for every 1000')

    And the answer is...

    208ºF – The boiling point of water decreases 1º Fahrenheit per 500’ above sea level, therefore at 2000' the boiling point would be 208ºF. However, if you live in Denver the boiling point drops to 202ºF. In La Rinconada, Peru, the highest permanent settlement in the world, you can boil water at 183ºF. Or if have the mad desire to boil some eggs at the top of Mount Everest you can get it done as soon as the water hits 162ºF.

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