Thursday, December 7, 2017

Compressed Air as a Motive Force

coalescing filters for compressed air
Coalescing filters are common components of a compressed
air system.
Image courtesy SPX Pneumatic Products
Compressed air is utilized throughout every industry and many commercial settings. While primarily used as a motive force, compressed air serves as a utility in many applications in the oil and gas, chemical and petrochemical, nuclear power, food, pharmaceutical, and automotive industries. The presence and use of compressed air across multiple industries is so essential, its importance is comparable to utilities like electricity, gas, and water.

In the control of fluid processes, compresses air facilitates operation and control of valves and other instruments. Dry air, with a sufficiently depressed dew point, can ensure process materials and equipment stay free of moisture and its associated impediments to smooth operation. The use of compressed air as either a motive force or a utility imparts minimum requirements on its quality or constituents. Confounding substances, such as particulates, water, and oil, may be entrained or contained in a compressed air stream. Various methods of filtration and moisture removal may be necessary to condition or process the compressed air in order to deliver consistent quality.

The advantages of using compressed air as a motive force in industrial settings are more numerous than appropriate for listing here, but consider that tools driven by compressed air can be more compact, lower weight and less prone to overheating than electrically driven tools. Air driven devices tend to have reduced parts count and require little maintenance, whether tools, valve actuators, pistons, or other machines. Compressed air driven devices can be fashioned to amplify the power of an electrical signal, enabling a simpler means of powering some types of loads. Compressed air, by its nature, presents no electrical hazards to the workplace.

Whenever air driven devices are utilized, attention must be given to compressed air production. The pressure, maximum flow rate demand, and compressed air quality must meet the process or operation requirements. Share your compressed air system challenges with specialists, leveraging your own knowledge and experience with their product application expertise to develop effective solutions.

Tuesday, November 28, 2017

Pipeline Cyber Security

binary stream representing industrial process control network data transfer and cyber security threat
Cybersecurity is a process control challenge that consistently evolves as new technologies come into use and new threats emerge. Since process control methods are constantly developing, the protective measures need to match the rate of change to ensure adequate levels of protection are in place. Pipelines used in the oil and gas industry, as well as in the transportation of a multitude of liquid and gaseous products, account for more than 2.3 million miles of process piping in the United States.  Natural gas pipelines are commonly monitored and controlled by, for example, programmable logic controllers or other microprocessor and communications based systems, responsible for flow regulation and various process conditions. Because of the prevalence of these systems, they are a target of increasing attacks, on both PLCs and other SCADA related devices, such as compressors, remote terminal units, communication networks, and other critical process infrastructure elements.

While developments in technology have provided operating advantages and improvements to the process industries, the more complex and advanced the systems may also increase the exposure to malicious penetration and mischief by unauthorized parties (hackers). Because of this, diligence by industry professionals, while always a strong component of protecting against outside threats, has been augmented via new guidelines meant to better prepare all process operators against more coordinated cyber-attacks.

Basic preventative measures, such as a firewall, are no longer a sufficient bulwark against the increasing threats. Instead, the entire process must be evaluated and monitored so that each individual piece of the network is understood fully. If a part of the system starts behaving in an abnormal way, then an understanding of what that specific PLC or component affects must be immediately known. The most effective protective programs will be able to function without needing any downtime, and will also be able to learn the network easily. Whenever the defense program gets triggered, it needs to not only provide a general alert to the process operator, but must also be able to provide context so that the previous knowledge of how the system works can be applied to mitigate the current problem.

Currently, the oil and gas industry has transitioned to what is being termed a ‘holistic’ approach to cyber defense. In order for the best security possible to be employed, the human element of process control must function in tandem with the autonomous programs. The human component of process operation, where it exists, can be unpredictable and present vulnerabilities that may not be known or anticipated. Everything must be considered.

Industrial process operation involves many areas of risk, with cyber attack being just one. The right kind of planning and response to risk can mitigate the potential impact. Security efforts, technology, and knowledge must keep pace with threats which emerge to process pipeline security. Mountain States Engineering and Controls participates in the oil and gas industry throughout the western U.S.

Thursday, November 16, 2017

Forced Draft Cooling Tower With 20 Year Warranty

corrosion resistant HDPE cooling tower rated 50 tons with forced draft
Forced draft corrosion resistant cooling tower
with forced draft, rated 50 tons. Pioneer series.
Image courtesy Delta Cooling Towers
Delta Cooling Towers specializes in the design and construction of corrosion resistant cooling towers and similar equipment. Much of the tower construction is HDPE or other non-metallic material, enabling the company to offer a 20 year warranty on their equipment.

Cooling towers are employed worldwide in HVAC applications and process fluid cooling. In addition to their industry leading corrosion resistance, Delta Cooling Towers also offers anti-microbial protection which combats the growth of microbes responsible for Legionnaires Disease and other respiratory ailments. The various product lines cover heat transfer capacities to accommodate any installation.

There is a lexicon employed in the description of cooling tower performance and operation. Some commonly used terms, along with their meaning, is provided below. The terms and their meanings is pulled from the owner's manual provided by Delta Cooling Towers for their Pioneer series of forced draft cooling towers.

Share your process and HVAC cooling challenges with application experts, leveraging your own knowledge and experience with their product application expertise to develop an effective solution.

Cooling Tower Terms and Definitions

  • BTU - A BTU is the heat energy required to raise the temperature of one pound of water one degree Fahrenheit in the range from 32° F. to 212° F.
  • Cooling Range - The difference in temperature between the hot water entering the tower and the cold water leaving the tower is the cooling range.
  • Approach - The difference between the temperature of the cold water leaving the tower and the wet-bulb temperature of the air is known as the approach. The approach fixes the operating temperature of the tower and is a most important parameter in determining both tower size and cost.
  • Drift - The water entrained in the air flow and discharged to the atmosphere. Drift loss does not include water lost by evaporation. Proper tower design and operation can minimize drift loss.
  • Heat Load - The amount of heat to be removed from the circulating water through the tower. Heat load is equal to water circulation rate (gpm) times the cooling range times 500 and is expressed in BTU/hr. Heat load is also an important parameter in determining tower size and cost.
  • Ton - An evaporative cooling ton is 15,000 BTU's per hour.
  • Wet-Bulb Temperature - The lowest temperature that water theoretically can reach by evaporation. Wet-Bulb Temperature is an extremely important parameter in tower selection and design and should be measured by a psychrometer.
  • Pumping Head - The pressure required to pump the water from the tower basin, through the entire system and return to the top of the tower.
  • Make-Up - The amount of water required to replace normal losses caused by bleedoff, drift, and evaporation.
  • Bleed Off (Blowdown) - The circulating water in the tower which is discharged to waste to help keep the dissolved solids concentrating in the water below a maximum allowable limit. As a result of evaporation, dissolved solids concentration will continually increase unless reduced by bleed off.

Friday, November 10, 2017

Hydrostatic Pressure Liquid Level Measurement

differential pressure tank level indicator
Tank mounted differential pressure transmitter
measures hydrostatic pressure to derive liquid level
Image courtesy King-Gage
Liquid level can be inferred by accurately measuring the pressure produced by the height of a fluid column and knowing the density of the liquid measured. The measurement is comparative in nature, referencing some external pressure as a zero point. The zero point can be the surrounding atmospheric pressure, tank pressure, or the pressure exerted by another column of liquid contained elsewhere.

There are uncountable application scenarios, each with its own set of special conditions. Proper instrument selection, installation and calibration are essential to generating reliable and accurate results.

The King-Gage TeleSensor™ liquid level transmitters are specially designed to provide level measurements across a wide range of liquids using a force balance principle in a pneumatic sensor. Sensor output can be either a pneumatic signal or 4-20 mA. The pneumatic force balance arrangement provides immunity to long term drift, hysteresis and temperature changes. A diaphragm isolates the sensor from the process liquid. Mounting is compatible with 2", 3", or 4" class 150 ANSI flanges. Various options for diaphragm and flange materials are available to accommodate a range of process media.

More detail is provided in the document included below, along with application examples. Contact product specialists to share your application challenges and get effective solutions.

Thursday, November 2, 2017

Steam Condensate Return Stations

duplex condensate return station
Duplex condensate return station
Image courtesy Roth Pump
Closed steam systems produce condensate, a dense source of heat. By design, the delivery of heat in a steam system is almost entirely accomplished using the heat of vaporization, with any sensible heat transfer probably being more coincidental than intentional. Condensate will contain most of the sensible heat that was added to the feedwater to get it to the boiling temperature. Conserving that sensible heat through a reuse of the hot condensate is a huge energy saving step. The condensate must be collected and returned to the boiler in a effective manner.

A condensate return station is a common means of moving condensate back to the boiler. It will generally consist of a collection vessel for the liquid condensate and one or more pumps to provide the motive force to move the liquid along its return path. Reliability is a key factor for these systems, since it is conceivable that they may need to perform on a continuous basis for years. A duplex pump arrangement can provide some backup, as well as extra capacity for accommodating large inlet flow. This is an installation where investing in rugged hardware can pay dividends in reduced maintenance burden and trouble free performance for the long term.

Roth Pump Company has been designing and manufacturing condensate return stations and other steam system related components for many years. Their experience and expertise are part of each and every system that leaves their factory. By incorporating low RPM motors, heavy duty pumps, and other features into a compact form factor, the company is able to offer a number of systems that meet a wide range of applications and deliver solid long term performance.

Share your steam system and condensate return requirements and challenges with application experts, leveraging your own experience and knowledge with their product application expertise.


Thursday, October 26, 2017

When to Use a Globe Valve for Fluid Process Control

cast iron globe valves
Cast iron globe valves are utilized extensively in steam,
HVAC, and other commercial and industrial applications
Image courtesy of Crane Co.
Industrial process control often involves the regulation of fluid flow. There are almost uncountable types and variants of flow control valves, each with a particular set of attributes that can make it the advantageous choice an application.

When the process calls for controlling flow over a range of possible values, known as throttling, a globe valve may be a good candidate for the application.

Globe valves are characterized by the change in direction of fluid flow as it passes through the valve and around the plug positioned in an opening through which fluid must pass. The plug is connected to a stem extending to the exterior of the valve body through the bonnet. Movement of the stem will reposition the plug in relation to the opening, providing a successively larger or smaller opening area through which fluid can pass.

Globe valves are available in tee, angle, and wye configurations, as well as an enormous range of special configurations to suit specific applications.
simplified globe valve diagram
Simplified globe valve diagram
Image courtesy Wikipedia


What are some potential advantages of globe valves?
  • Good throttling and shutoff capability
  • Comparatively easy maintenance
  • Comparatively short travel of plug from open to closed position
  • Seats can usually be resurfaced when worn
What are some limiting factors for globe valves?
  • Higher valve pressure drop than some other designs
  • No straight through fluid path
  • Potentially higher actuator torque requirements than other valve types
  • Seal area is unprotected from exposure to process fluid flow
When flow throttling capability is the overriding concern for an application, a globe valve is a good candidate for consideration. Share your flow control challenges with valve and automation specialists. Combining your process knowledge and experience with their product application expertise will produce effective solutions.

Friday, October 20, 2017

Wet Bulb Temperature and Cooling Tower Performance

corrosion resistant cooling tower induced draft type
Corrosion resistant evaporative cooling tower
Image courtesy Delta Cooling Towers, Inc.
Evaporative cooling towers enable many buildings across the globe to enjoy moderate interior temperatures. They serve as the final heat transfer step that moves heat from the building interior to the surrounding environment. In addition to their extensive application throughout large residential, commercial and industrial HVAC systems, their are numerous process cooling applications that employ evaporative cooling towers as an effective means of heat rejection.

Delta Cooling Towers, Inc. is a globally recognized manufacturer of corrosion resistant cooling towers, air strippers and tanks fabricated of HDPE to provide extended life service. The company posted an article entitled "Understanding Wet Bulb Temperatures And How It Affects Cooling Tower Performance". The original post is on this page of the company website, and all credit for the article goes to them. We share it below also, slightly edited for format on this forum.  From the article...

A cooling tower primarily uses latent heat of vaporization (evaporation) to cool process water. Minor additional cooling is provided by the air because of its temperature increase. Cooling tower selection and performance is based on water flow rate, water inlet temperature, water outlet temperature and ambient wet bulb temperature. Ambient wet bulb temperature and its affect on performance is the subject of this article. Ambient wet bulb temperature is a condition measured by a device called a psychrometer. A psychrometer places a thin film of water on the bulb of thermometer that is twirled in the air. After about a minute, the thermometer will show a reduced temperature. The low point when no additional twirling reduces the temperature is called the wet bulb temperature. The measured wet bulb temperature is a function of relative humidity and ambient air temperature. Wet bulb temperature essentially measures how much water vapor the atmosphere can hold at current weather conditions. A lower wet bulb temperature means the air is drier and can hold more water vapor than it can at a higher wet bulb temperature. For example:
Since cooling tower cells cool water by evaporation, the wet bulb temperature is the critical design variable. An evaporative cooling tower can generally provide cooling water 5° - 7° higher above the current ambient wet bulb condition. That means that if the wet bulb temperature is 78°F, then the cooling tower will most likely provide cooling water between 83° - 85°F, no lower. The same tower cell, on a day when the wet bulb temperature is 68°F, is likely to provide 74° - 76°F cooling water. When selecting a cooling tower cell, the highest or the design wet bulb temperature your geographical area will encounter must be used. Highest wet bulb temperatures occur during the summer, when air temperatures and humidity is highest. For example, in Indianapolis, Indiana, the design wet bulb temperature is 78°F. Historically Indianapolis can expect less than one hour per year that the conditions exceed a 78°F wet bulb. Typically, 6,000 hours a year will have a wet bulb of 60°F or lower meaning that a cooling tower cell designed for a 78°F wet bulb will be able to make 65-67°F water for 6,000 hours per year nearly 70% of the year. Most cooling towers are capacity rated at a "standard" wet bulb temperature of 78°F. That means on the days when the wet bulb temperature is 78°F, the tower will produce its stated capacity. In other words, a tower rated to produce 135 tons of cooling will produce 135 tons of cooling at a 78°F wet bulb temperature. At a higher wet bulb temperature, the tower cell capacity to produce colder water decreases. Every location has a unique design (worst case) wet bulb temperature that is published by organizations such as ASHRAE and can be obtained easily.

What does it mean when your cooling tower water temperature is higher than the normal 5-7°F above the current wet bulb temperature?

  1. Your cooling load may be larger than the rated capacity of your cooling tower.
  2. Your cooling tower may have lost efficiency
  • Due to scale build up on the tower heat exchange surfaces.
  • Due to loss of air flow across the heat exchange surfaces.
  • Due to improper water flow from clogged nozzles or pump performance
What can you do to improve your tower performance? 

  • Add tower cell capacity
  • Check for the efficiency losses described above
  • Replace the heat exchange surfaces with new clean fill
  • Check for proper airflow
  • Check the water flow is at design
  • Check that nozzles are not clogged or broken


Cooling tower performance is tied to ambient wet bulb conditions. Higher wet bulb temperatures occur in the summer when higher ambient and relative humidity occurs. Initial system design and proper system maintenance is critical to be certain your cooling tower is providing desired cooling.

For more information, or to discuss your own heat transfer challenges, contact a product application specialist. Combine your own knowledge and experience with their application expertise to develop an effective solution.