April 2011 Newsletter

CAS Newsletter April 2011

Volume #9, Newsletter #9 April-2011
Chipkin Automation Systems Inc.


Federal Commercial Building Tax Deduction

The Federal Commercial Building Tax Deduction will end on December 31, 2013

Companies who invest in the installation of energy-efficient commercial property can claim the CBTD that covers up all deductible cost, up to $1.80/sq.ft. for the projects completed on or before Dec 31, 2013.

Indoor lighting systems AND HVAC/hot water systems AND Building envelope features

Some requiremetns must be met to qualify for The Federal Commercial Building Tax Deduction. According to EPAct 2005 and IRS Notice 2006-52:

  • The total annual energy and power cost of the approved project must be decreased to minimum 50% less than a Reference Building to meet the requirements of ASHRAE/IESNA 90.1-2001, by changing the building’s lighting system, HVAC/hot water systems and building envelope features only;
  • If not, then the cost must be depreciated for tax purposes;
  • The project involves in a new construction or renovation project must meet the requirements stated in ASHRAE/IESNA 90.1-2001. (including addenda 90.1a-2003—transformers, 90.1b-2002—building envelope, 90.1c-2002—ducts, 90.1-d-2002—slab-on-grade floor insulation, and 90.1k-2002—piping insulation, as in effect as of April 2, 2003); and
  • The location of the project must be in the United States or its territories.

Lighting Controls

Section 9.1/Compliance: Interior Lighting

If the lighting system is not installed in the building interior, then the company is disqualified for the Commercial Building Tax Deduction.

If it is, a few more questions about the functionality and the location of the lighting must be answered by yes, in order to be exempted from Standard 90.1. Otherwise, follow the applicable Standard 90.1-2001 and prescriptive interior lighting provisions 9.2 + 9.3. If the code application is required, follow all other applicable state and local code requirements.

(click on the image for a better view)

Section Lighting Control Provisions: Automatic Shut-off

The very first question being asked is if the building where the interior lighting installed is larger than 5,000 sq.ft. If the building is smaller, then the building is exempted from mandatory automatic shut-off requirements, and the company can proceed to Section Control directly.

If the building is larger than 5,000 sq.ft, the lighting must be utilized for non-stop operation so the lighting will be exempted from automatic switch-off requirements and the company can then proceed to Section Control. Otherwise, all interior lighting is required to have automatic switch-off control. Choose one of the three switch-off control methods (based on Time Program, Occupancy Sensor or Unoccupied Signal) before proceed to the final step, which is Section Control.

Section Lighting Control Provisions: Additional Control

Each type of lighting must have an individual control unit. If the building is a hotel or motel, a master control unit must be installed at the main entry of each hotel guest room to control all fixtures and switched outlets.
Task lighting control must be integrated with light fixture and mounted on wall where it is conveniently and visibly located.
If the above requirements are all met, then proceed to Section 9.2.4/Installed interior Lighting Power and Section 9.2.5/Luminaire Watage.

Level Sensing

Floats & Displacers

Floats and Displacers are simple level measurement devices. They are somewhat identical in their look but they work on different operating principles.

Float level switches work upon the buoyancy Principle according to which as liquid level changes a (predominately) sealed container will, providing its density is lower than that of the liquid, move correspondingly. In other words, the buoyancy principle states that the buoyancy force action on an object is equal to the mass of liquid displaced by the object.

Displacers operation is based upon the Archimedes Principle which says that when a body is immersed in a fluid it loses weight equal to that of the fluid displaced. By detection of the apparent weight of the immersed displacer, a level measurement can be inferred.

Displacers and floats are strictly applied for level detection in case of moderately non-viscous and clean process liquids. They present their best operation in switching applications and over for small periods. One can achieve spans of up to 12m also, but in that case their use happens to be extremely costly.

Float Level Switches

Float level switches are mainly employed for level measurement in narrow level differential fields, for example high level alarm or low level alarm applications. One of the significant types of float is a magnetrol float level switch which consists of a plain float and operates via a magnetic coupling action. The switch is designed in such a way that some part of float remains submerged in the liquid as it rides on the liquid surface. The float goes up and down on the surface depending upon the level of fluid in the tank. This causes a magnetic sleeve to travel in or out of the region of a magnetic switch resulting in its activation. A non-magnetic tube is also provided in the design which acts as a barrier and helps in separating the switching arrangement from the controlled fluid. Float level switches exist in diverse shapes such as spherical, cylindrical and many other forms as shown in the figure below.

These float based level switches include: a magnetic piston, a reed switch and a mercury switch. Among different float switch designs, the oldest and most precise one employed for continuous level detection is the tape level gauge. Float level sensors are usually prepared from materials like stainless steel, PFA, Hastelloy, Monel, and several other plastic components. It is always required of floats to have their weights less than the minimum likely specific gravity of the liquid being measured. There are basically three kinds of Float level controls which are listed below:

  1. Top mounting
  2. Side mounting
  3. External cage

Figures indicating Top mount and Side mount operating principles are shown below.

Top Mount Operating Principle

Side Mount Operating Principle

An extensive choice of float level switches is accessible in the market which may include mercury, dry contact, hermetically sealed and pneumatic switching devices. The upper temperature and pressure limits of float level switches are +1000° F and 5000 psig respectively. They usually work with low specific gravities which can be around 0.32. They exist in variety of models such as single, dual and three switch models. Besides, for level detection of interfaces created between two fluids, customary float rides are available. Float operated control valves are also available which basically perform combined functions of level detection as well as level control via a single level controller. However, their use is limited to areas involving small flows with negligible pressure drops only.

Displacer Switches

In a typical displacer switch design, a spring is provided which is burdened with weighted displacers. The displacers having weights greater than the process fluid gets submerged in the liquid resulting in a buoyancy force change. This will cause a variation in the net force operating on the spring. In general, the spring will compress with the raise in buoyancy force. Just like the float level switches, a magnetic sleeve and a non-magnetic barrier tube is also incorporated in displacer switches. The magnetic sleeve is attached to the spring and it moves according to the spring movement resulting in activation of switching mechanism. An in-built limit switch is provided in the design which proves useful in level surge conditions since it keeps a check on the over stroking of the spring. The operating principle of a typical Displacer switch is illustrated in the figure below.

Displacer switches are most commonly employed in oil and petrochemical fields as level transmitters and local level controllers. These switches offer extremely correct and consistent measurement results in applications where clean liquids having stable densities are concerned. They are particularly not appropriate for slurry or sludge type applications since coating of the displacer causes a change in its volume and a resulting change in its buoyancy force. Temperature adjustments should also be done for these switches, specifically in areas where changes in process temperature can significantly affect the density of the process liquid.

The performance of displacers can be influenced by non-stability in process density in view of the fact that the displacement i.e. the weight loss of the material is equivalent to the weight of the liquid dislocated. As soon as the specific gravity of the process varies, the weight of the displaced material also varies accordingly, resulting in a change in the calibration. Due to this, one can specifically face problems in cases of interface level detection between two liquids having different densities, where the relative signal depends upon the difference between two densities. An important requirement while working with displacers is that even after commissioning, the liquid being detected must retain its density for getting good repeatability.


Following are the major advantages associated with the use of floats and displacers:

  • They perform extremely well with clean fluids.
  • Use of these level sensors proves to be very accurate.
  • They are flexible to extensive changes in density of the medium.

Floats v/s Displacers

Following are the major points of distinction between floats and displacers:

  • Float Switches are available with a glandless design and are capable of fail safe operation in extreme process conditions, unlike displacers, which if the torque tube fails can provide a leak path.
  • A float generally rides above the surface of liquid whereas a displacer remains either partly or totally immersed in process liquid.
  • Displacer switches are considered to be additionally stable and dependable as compared to standard float level switches in case of turbulent, surging, frothy and foamy services. However in case of refineries, the use of displacers is decreasing owing to their high installation cost and inaccurate performance due to process density changes. In these applications, float level switches have been found to be reliable and useful.
  • Settings of displacers can be changed very easily since they can be shifted at any place along the length of the suspension cable. Moreover, these level devices have the provision of interchangeability between tanks. This is due to the fact that the differences in process density can be endured by varying the tension of the spring attached to the displacers.
  • Testing the appropriate working of a displacer switch is much easier than a customary float level switch since the former requires just lifting of a suspension whereas the latter necessitates filling of liquid in the tank upto the actuation mark.


Ultrasonic Level Measurement

Level measurement can be performed via ultrasonic or sonic technology too. Ultrasonic level measurement devices basically employ sound waves for detection of liquid level. They usually work over the frequency range between 20 kHz to 200 kHz.

Operating Principle

The working principle of a typical Ultrasonic level sensor is illustrated in the figure below.

In this design, the level sensor is located at the top of the tank in such a way that it sends out the sound waves in the form of bursts in downward direction to the fluid in the tank under level measurement. As soon as the directed sound waves hits the surface of the fluid, sound echoes gets reflected and returned back to the sensor.

The time taken by the sound wave to return back is directly proportional to the distance between the piezo electric sensor and the material in the tank. This time duration is measured by the sensor which is then further used to calculate the level of liquid in the tank. The speed of the sound waves can sometimes be affected due to variations in temperature for which appropriate compensations need to be provided in the sensor design. In general, the medium over the fluid’s surface is air. However, one can employ a blanket of nitrogen or any other vapor also.

Types of Ultrasonic Level Sensors

Ultrasonic level sensors are available in two basic types which are explained below:

Non-Contact Ultrasonic Sensors

This category of ultrasonic level sensors consists of:

  1. An analog signal processor
  2. A microprocessor
  3. Binary coded decimal i.e. BCD range switches
  4. An output driver circuit

In these devices, the microprocessor generates the gate signal and pulses and directs them to the ultrasonic sensor via the analog signal processor. The sensor then transmits a beam of ultrasonic waves to the surface of the fluid. It also receives the reflected echoes from the fluid surface and sends them back to the microprocessor. The microprocessor keeps on receiving echoes of sound waves and performs calculations to determine distance between the sensor and the fluid surface and hence detects the fluid level.

Contact Ultrasonic Sensors

These types of ultrasonic sensors are primarily used to detect fluid level at a specific point only. These level measurement devices consume less energy and basically include:

  • A sensor installed in the process field and
  • An integrated solid state amplifier

They consist of no movable parts and hence do not need any calibration. Typically, they are equipped with terminal blocks for connection of a power source and external control devices. The ultrasonic signal crosses a one-half inch gap in the sensor, controlling relay switches when the gap contains liquid. The sensing level is midway along the gap for horizontally mounted sensors, at the top of the gap for vertically mounted sensors. When the level of the fluid drops below the sensing level, the strength of the ultrasonic signal gets reduced. This eventually brings the relay to its former position.

These ultrasonic sensors find their application in vessels or pipes where they are used for automatic action of pumps, solenoid valves, and high or low level alarms. In these areas, two sensors need to be employed: one for filling and emptying tanks and the other one for measuring fluid volumes. They are suitable for use with mostly all kinds of fluids. Their performance does not get easily influenced by coatings, clinging droplets, foam or vapor etc but sometimes, highly aerated or viscous fluids can create trouble by choking the sensor gap.

Main Features

Key features of ultrasonic level measurement devices are listed below:

  • These sensors use frequencies in the tens of kilohertz range; transit times are ~6 ms/m. The speed of sound (340 m/s in air at 15°C (1115 fps at 60°F) depends on the mixture of gases in the headspace and their temperature.
  • The speed of sound waves traveling via the medium which is normally air is prone to get affected by changes in the working temperature. In order to compensate for these changes in temperature and resulting changes in sound wave speed, the level measurement system must include a temperature sensing device. This will help in correct distance calculations and hence accurate level detection results.
  • In cases where heavy foam is found on the surface of the process fluid, the use of ultrasonic level measurement techniques are usually avoided since this foam work as a sound absorbent. Consequently, the sound wave will get scattered resulting in non reception of the exact signal by the sensor. This will cause improper functioning of the measurement system.
  • Excessive surface turbulence of the fluid can result in wide fluctuations in level measurement results. To avoid this issue, one may employ a damping correction or a response delay with the device.
  • Good level measurement requires that the reflected echo from the fluid surface returns back in a straight line to the sensor. Besides, it calls for proper installation of ultrasonic transmitter over the tank. The transmitter should be mounted in such a way that the inner composition of the vessel or tank doesn’t get in the way of the signal.
  • In level measurement fields where sound waves get influenced by factors like foam and vapor etc., one can connect a beam guide to the sensor for improving performance of these devices.
  • Ultrasonic level measurement technique proves to be quite costly when employed for point level measurement applications.
  • In case of fluids which are less viscous, one can execute point level measurement via a technique called ultrasonic gap technique. In this method, a transmit crystal is activated on one side of a “measurement gap” and a receive crystal listens on the opposite side. The signal from the receive crystal is analyzed for the presence or absence of tank contents in the measurement gap.
  • To overcome barricades encountered in the vessel or tanks, a technique called tank mapping has been introduced. Tank mapping lets the operator take a “sonic snapshot” of an empty vessel. The transducer transmits a sound burst and the echo is recorded as a signature of the tank. Any obstructions in the vessel will send an echo and create a profile. Later on, this signature or profile is locked into the ultrasonic unit’s memory so it will not respond to echoes created by these obstructions.


Major advantages offered by ultrasonic level measurement technique are mentioned below:

  • Ultrasonic level sensors are usually non contact type i.e. they do not make any contact with the process fluid under level detection.
  • Besides, they consist of fixed components only hence require less maintenance
  • They are usually mounted at the top of the vessel due to which they are less likely to offer leakage problems as compared to entirely wetted means.


Ultrasonic level measurement technique can not be suitably applied in all fields since use of ultrasonic level sensors includes few setbacks too. Many factors exist which have the tendency to influence the returned echo signal back to the sensor. Some of them include:

  • Materials like powders etc.
  • Heavy vapors
  • Surface turmoil
  • Foam
  • Ambient noise and temperature

Besides, ultrasonic level measurement devices do not work satisfactorily in areas involving vacuum or high pressure conditions.


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Case Study – Carlo Gavazzi Integration

We integrate Variflex RVCF and RVEF drives on ANY Automation Protocol

CAS specially configured a ‘Gateway’ which connects one or more trunks of drives for conversion to BACnet, Lonworks, Rockwell, Omron, GE, Johnson Metasys N2 and many more.

You may now expand your reach and make your customers happy by offering Variflex drives on ALL protocols.

Take advantage of our special Carlo Gavazzi Variflex config software for quick and effective integration.

The customized configuration software lists parameters and makes selection for gateway mapping onto BACnet (or other protocols) easy.

CAS connects Carlo Gavazzi Energy and Power equipment on ALL Automation Protocols.

If a customer wants to buy Carlo Gavazzi UDM60 Panel Meters and Power Quality Analyzer Type WM5-96

  • He/She wants to integrate these with his Metasys N2 controller
  • But the Panel meters and the Power Quality Analyzer support ONLY Modbus RTU

No worries, just make the sale!!! We will do the protocol integration.

Why Us?

  • Safe Hands: We have over a decade of experience in protocol integration
  • We have been closely working with Carlo Gavazzi and know their equipment very well
  • Custom tools Specially for Carlo Gavazzi equipment: our long experience with Carlo Gavazzi has enabled us to develop special config tools for their equipment

Amazing Engineering – Chinese built a 15-story hotel in six days

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