Monday, September 12, 2016

Temperature Control by Fenwal

Anderson-Bolds and Fenwal Discussion of Temperature Control and Controllers

Contact Anderson-Bolds HERE.


The results you get with a precision temperature controller, as with any tool, depend on how skillfully it is used. It will produce close control only when the design and operating conditions of the system help it to respond quickly and accurately.
A controller is only one part of a heated system. Its job is to sense temperature at a particular point in the system, and, on the basis of what it senses, actuate some other device which changes the quantity of heat flowing into the system. A controller can respond only to what it sees at its particular location. It cannot react to a temperature rise or fall somewhere in the system until that information arrives at the sensing element. Generally, it cannot compensate for too much or too little heat being put into the system when the heat source is improperly sized. And, most important, it has no way of recognizing whether the temperature in its vicinity truly represents the temperature at the work area. Regardless of the capabilities of the controller, it can control no more closely than the design of the system permits.

1. Heated System?
There are four elements in a heated system, ail of which contribute in some way to control performance.

A. Work (or Load): The material or product which must be maintained at a controlled temperature. The heat demand of the work may be steady; that is, the same material must be held at constant temperature for a prolonged period, such as a culture in an incubating oven. More commonly, the heat demand of the work is variable and cyclic; that is, cold material periodically enters the system, absorbs heat, is removed and replaced by another batch of cold material. An example of a variable system is a molding press which receives a batch of cool plastic, forms, cures and ejects it and repeats the cycle several times a minute.

B. Heat Source: The device which delivers the heat used by the system. The source may be electrical heaters, oil and gas-fired heaters, or any other source. The process may be exothermic; i.e., generate its own heat.

C. Heat Transfer Medium: The material which transmits the heat from the heat source to the work. The material may be a solid, liquid, or gas. Its transfer characteristics play a large part in determining how fast temperature changes are transmitted through the system and, consequently, how closely the system can be controlled.

D. Controller: The instrument which controls the heat flow on the basis of the discrepancy between the sensed temperature and the controllers set point.

2. The Meanings of “accuracy”.

The term "control accuracy" is frequently used rather loosely to denote several distinct and different concepts. For the sake of clarity, these concepts will be labelled and discussed briefly. (See Figure 1)

A. System Bandwidth: the total temperature variation—measured at some point in the system, usually at the work area. For example (See Figure 1), if the maximum and minimum temperatures in a system are 203 and 199°F, the bandwidth is 4 degrees. (Commonly this is referred to as ± 2°, though correct expression is 4°.)

The sensitivity of the controller contributes only partially to determining the bandwidth; several other factors relating to the over-all system (described in the following sections ) contribute importantly and sometimes decisively. Maintaining a very narrow bandwidth may be the primary goal to prevent overshoot in products or processes which are being heated close to their decomposition, vaporization or other critical point. Narrow bandwidth, by itself, does not guarantee constant temperature, since the mean temperature can drift. In many cases, constancy of mean temperature is relatively more important than a narrow bandwidth.

B. Mean Temperature: the numerical average of the maximum and minimum temperatures reached at some point in the system. For example (See Figure 1)  for a maximum of 203 and a minimum of 199, the mean temperature is 201. In a large number of systems, maintaining the mean temperature relatively constant, rather than maintaining a very narrow bandwidth, is the practical objective. The mean temperature (also referred to as the "control point") may or may not be the same temperature as the controller's set point. When they are not die same, an offset exists.

C. Offset: the difference between any two temperatures, such as between the setting of the controller and the mean temperature of the load when the system is at a steady state. In Figure 1, the offset is 1°.

D. Controller Operating Differential: the difference between sensing element temperature at make and break of the controller's contacts when the controller is cycled in a specified control system. For example (Figure 1), when the controller's contacts are closed at 200.6 and open at 201.4, its operating differential in that particular system is 0.8 degrees. For some types of controllers the operating differential is affected by electrical load, set point and physical location, so that it is usually larger than the controller's resolution sensitivity.

E. Controller Resolution Sensitivity (sometimes called inherent sensitivity) : the minimum temperature difference necessary to operate the controller's contacts under ideal conditions.

3. A Practical Approach to Accuracy

The user of a thermal system is interested in one basic question: is the temperature control accurate enough to operate his product or process satisfactorily? Control requirements are far less stringent in a waffle iron than in a crystal oscillator oven. Maintaining exact temperature in a wax applicator tank is less critical than in a laboratory viscosimeter. The point is that exact control of a system takes time, care and money. Moreover, it takes highly sensitive measuring instruments and indicators—and frequent recalibration in service—to tell just how good the control is. Eliminating the last degree or fraction of a degree of temperature deviation is costly and should be done only for sound practical reasons.
Nonetheless, good control is attainable with standard instruments. To be sure, control will be no better than the capabilities of the controller, but unless the system is designed as an entity, there is little assurance that the controller can deliver what the user expects of it.

4. What Affects Control Accuracy?

System bandwidth and constancy of mean temperature are the overall measures of control accuracy. They are affected by many factors:
A. Temperature Gradients—the range of temperature variation throughout the system at any given instant.
B. Thermal Lag—the time delay for a temperature change in one part of the system to be felt in other parts of the system.
C. Location of the Controller's Sensing Element—its placement relative to heat source and load.
D. Response Speed and Sensitivity of the Controller—these and other characteristics make up inherent controller accuracy. They determine how well it is suited for a given application.
E. Heat Balance—the capacity of the heat source in relation to heat demand from the work, plus heat losses.

5. How Heat Moves

Heat, like water, seeks its own level. It moves only from a higher to a lower temperature zone at a rate depending on the temperature difference and the conductivity or emissivity of the heat transfer medium. The three methods of heat transfer are: conduction, convection and radiation.

A. Conduction takes place in solids, liquids and gases. The heat is transmitted in a kind of chain reaction by the rubbing action of a "hot" or higher energy particle with an adjacent "cool" lower energy particle, while the particles remain in the same relative position to each other. A commonplace example is the gradual heating of the upper end of a spoon when the lower end is immersed in a hot cup of coffee.

B. Convection takes place in liquids and gases. It occurs when a stream of warm particles rises, mixes and diffuses into a cooler area. Convection from a heat source at the bottom of the structure is a common method of heating ovens and water tanks. Natural convection currents move slowly and it requires a fairly long time for a container of any reasonable size to reach uniform temperature. This makes accurate control practically impossible. When good control is demanded in ovens and liquid baths, forced convection, produced by blowers, agitators or recirculation lines will be necessary.

c. Radiation is a form of energy transmission which is emitted from a heated body. Radiant energy needs no heat transfer medium and thus can travel in a vacuum. The most familiar example of radiant energy is sunlight, which travels through the nearly empty outer space, the denser atmosphere of the earth and is finally absorbed by buildings and pavements. These structures then act as secondary heat sources by radiating much of the absorbed heat back to the surrounding atmosphere.
In most systems all three methods of heat transfer are present. A platen, internally heated by an electric heater, heats the work by conduction. However, heat may be lost from the surfaces of the platen both by convection and conduction to metal parts touching the platen. In an oven the walls and internal structures also become heated and these in turn radiate and convect heat back into the oven cavity.
These secondary heat sources, while useful in maintaining a stable heat level in the system, can nevertheless cause difficulty in a closely- controlled system by creating local concentrations of heat which can bias the sensing element if it is not properly shielded. Conduction and radiation of heat away from the sensing element by supporting fittings and fastenings can similarly produce a sensing error. Thus, the various ways in which heat moves in and out of a system have a direct, practical influence on temperature control.

Contact Anderson-Bolds HERE to discuss your temperature control application.


Since 1934
Cleveland, Ohio

Wednesday, September 7, 2016

Calculating Heat Kilowatts and Specific Heat Values

Anderson-Bolds has been providing heating solutions to industry since 1934.

Here is the quick and simple heating equation and variables needed to heat an application.

Required BTU's or KW are calculated with this equation.

WxSHxΔT =BTU/hour

Weight (lb) of material being heated = W
Specific Heat of material = SH
Change in Temperature needed or Delta T = ΔT

To Convert BTUs to KW, divide the BTUs by 3413.

This equation only yields the heat input and does not take into consideration any heat losses or heat gains within a process. If an application is heating water but then a solid piece of metal enters into the water, the solid mud be heated too as well as the tank to achieve the goal system KW required.

Below are specific Heat values for common substances along with weights.
Specific Heats listed are all below 1 except Water which is 1.

Solid weights are per cubic foot and liquid weights are per gallon in pounds.

Aluminum   .23 SH  and  160 pounds
Asphalt       .40  and  65 pounds
Brass    .10  and 525 pounds
Bricks/masonry  .22 and 140 pounds
Carbon  .204  and  ??
Copper  .10  and  550 pounds
Glass   .20  and   165 pounds
Graphite   .20  and  130 pounds
Iron  .13  and  450 pounds
Lead  .031   and   710 pounds
Nickel  .11  and  550 pounds
Paper   .45  and   58 pounds
Paraffin  .70  and 56 pounds
Rubber  .40  and  95 pounds
Silver  .057  and  655 pounds
Solder   .04  and  580 pounds
Steel   .12  and  490 pounds
Sugar  .30  and 105  pounds
Sulphur   .203  and  125 pounds
Tin  .56  and 455 pounds
Wood (oak)  .45  and 50 pounds
Wood (pine)  .45  and 34 pounds

Acetic Acid  .472  and 8.81 pounds
Alcohol  .65  and 7.35 pounds
Benzine  .45  and 7.49 pounds
Ether  .503  and  6.15 pounds
Glycerine   .58  and 10.58 pounds
Mercury  .0333  and  113  pounds
Oil   .47   and  7.76  pounds
Petroleum   .51  and 7.49 pounds
Turpentine   .41  and   7.22 pounds
Water   1.0  and  8.34  pounds  (Most Difficult to Heat)

Please contact Anderson-Bolds HERE to discuss your heating process or application.

Since 1934

Sunday, August 21, 2016

Carlo Gavazzi Motor Thermistor Relays

Anderson-Bolds can supply Motor Thermistor Relays for Monitoring Motor Temperatures

Carlo Gavazzi is pleased to announce their new DTA7 Series of Motor Thermistor Relays. They are capable of monitoring the temperature of up to six motors (via thermistors on the internal windings). This type of monitoring and control prevents false alarms, which may cause interruptions in production and expensive machine downtime.

There are also numerous improvements from our prior design, such as universal power supply (which reduces the available part numbers choices by 67%) and a bi-color LED which, through different colors and blinking statuses, provides diagnostics, i.e. Power ON, PTC failure(s), Alarm and the ready to RESET state.

One or two output versions are available to facilitate control of the motor(s), with two output devices having the ability to control other auxiliary devices, such as an alarm indicator lamp, PC or PLC.

The Carlo Gavazzi DTA7 Series are useful in most applications where motors are used, especially where overloads are frequent and may cause motor damage, i.e. pumping stations in water treatment, conveyors in materials handling and chillers in HVAC systems.

Main features of the DTA7 Series include:

35.5 mm Mini DIN housing, with screw terminals

1 SPDT (DTA71) or 2 SPDT relay output (DTA72)

Relay contacts are NEMA B300 rated @ 240 VAC

Output 1 is DE-ENERGIZED on alarm (DTA71/DTA72)

(Optional) Output 2 ENERGIZED on alarm (DTA72)

For pricing use our Carlo Gavazzi Parts Form


Sunday, July 31, 2016

Carlo Gavazzi IP 69K PD30ET Photo Electric Sensors

Anderson-Bolds Sells the IP69 Stainless Steel Sensors from Carlo Gavazzi

July 2016 – CARLO GAVAZZI is proud to announce the launch of their new series of IP69K stainless steel photoelectric sensors, the PD30ET Series.
The new PD30ET Series complements the already popular PD30 photoelectric sensors, with robust AISI316L stainless steel housings. With an IP69K environmental rating and ECOLAB certification, reliable operation is ensured even in the harshest of environments. The PD30ETprovides outstanding resistance to high-pressure wash-down, aggressive cleaning agents, harsh disinfectants and high temperatures frequently found in the Food & Beverage industry. The PD30ET is also ideal for other harsh environments, including Material Handling, Packaging, Agriculture, and Mobile Equipment.

Main features of the PD30ET Series include:
Industry standard dimensions:
  - Housing: 11 x 21 x 31.5mm
  - Mounting: 25.4mm spacing, (2) M3 holes
AISI 316L stainless steel housing
NO and NC outputs, NPN or PNP versions
10–30VDC power supply
IP67, IP68 and IP69K ratings
cULus, ECOLAB, and CE approved
Top potentiometer set-up
Connections: 4-pin M8 plug or 2m cable
The PD30ET Series includes the following sensing types:
Diffuse reflective:
  - Extremely wide-angled (up to 200mm)
  - Long range (up to 1m)
Background Suppression, Active Pixel Sensor:
  - Visible red light version (up to 200mm)
  - Infrared version (up to 200mm)
  - Polarized visible red light (up to 6m)
  - Non-polarized infrared (up to 6m)
Through-beam versions (up to 15m)


Saturday, June 25, 2016

Jefferson ZERO Minimum Pressure Valves

Anderson-Bolds sells ZERO min pressure differential valves by Jefferson

Click here to View the Jefferson 1314 Series ZERO Minimum Valves

The Jefferson 1314 Series valves in sizes from 3/4 inch NPT to 3 inch NPT are designed to be very rugged and to be used in industrial applications. The hung piston valves require no differential pressure to close or open and the Normally Closed valves will remain open until de-energized.  This is a trait need to drain large tanks, like fuel or gasoline tanks.  Paired with a NEMA 7 housing makes these valves the perfect choice for oil and gasoline tank yards.

•Large Tank Draining
•Pumps of re-circulation for cold or hot water. 
•Heating with low or high pressure steam.
•Laundry equipments.
•Spraying. Irrigation. Dishwashers.
•Air dryers. water treatment. Vacuum systems 

Main characteristics:

Normally closed.
Pilot operated.
Bronze, stainless steel body.
BSP or NPT threaded connection.
Brass, stainless steel piston, among others.
Coil: Encapsulated up to 150 °C (302 °F) and coated with glass fibre and insulating impregnation up to 180 °C (356 °F), (for steam).

Interconnection cables. Internal general use housing. 3/4 ” NF electric connection.
Core: 430 F s.s.

•Explosion and / or weather proof housing. 
•Manual operator on the main orifice. 
•Flanged connections. 

2 inch valve with flange connections

Jefferson Brass Solenoid Valve Z1314BV06AT
120/60, 3/4 Inch NPT, NEMA 4/7, 0 PSI min, 105 max, N.C., Viton Seals

Jefferson Stainless Solenoid Valve Z1314SV06AT
120/60, 3/4 Inch NPT, NEMA 4/7, 0 PSI min, 105 max, N.C., Viton Seals

Jefferson Stainless Solenoid Valve Z1314SV08AT, 120/60
1 Inch NPT, NEMA 4/7, 0 PSI min, 105 max, N.C., Viton Seals

Jefferson Stainless Solenoid Valve Z1314SV12AT
120/60, 1-1/2 Inch NPT, NEMA 4/7, 0 PSI Min, 105 max, N.C., Viton Seals

Jefferson Brass Solenoid Valve Z1314BV12AT
120/60, 1-1/2 Inch NPT, NEMA 4/7, 0 PSI min, 105 max, N.C., Viton Seals

Jefferson Brass Solenoid Valve Z1314BV16AT
120/60, 2 Inch NPT, NEMA 4/7, 0 PSI min, 105 max, N.C., Viton Seals

Jefferson Stainless Solenoid Valve Z1314SV16AT
120/60, 2 Inch NPT, NEMA 4/7, 0 PSI min, 105 max, N.C., Viton Seals

Z6214BLVGA Bronze Jefferson Valve
120/60, 3 Inch NPT, NEMA 4/7, 0 PSI min, 105 max, N.C., Viton Seals

Z6214SLVGA Stainless Steel Jefferson Valve
120/60, 3 Inch NPT, NEMA 4/7, 0 PSI min, 105 max, N.C.

Valves can come with other voltages as well.  24vdc, 240 vac, 24 VAC, 480 vac

Click HERE to contact Anderson-Bolds

Tuesday, May 31, 2016

Barksdale Explosion Proof Pressure Switches D1X and D2X Series

Explosion Proof Diaphragm Pressure Switches from Barksdale and Anderson-Bolds

Contact Anderson-Bolds : Click HERE.

Barksdale, a World leader in Pressure switch design and manufacture, has updated their diaphragm series pressure switches with ATEX approvals for hazardous locations and environments. The Barksdale series D1X and D2X (single and dual set) switches are the industry standard for mechanical diaphragm pressure switches.  Barksdale D1X and D2X switches can be found used for pump and compressor monitoring, hydraulic units, the oil and gas industry, food and beverage, utility and power generation and in the mining industry as well as general industry where hazardous areas are present.

The features of the Barkdale D1X and D2X pressure switches are: hermetically sealed, Tamper Proof Adjustment, pressure or vacuum applications, UL, CSA and ATEX approved and NEMA 4, 7, 9 and IP66 housing.

Accuracy: ± 0.5% of the adjustable range
Switch Rating: 10 Amps @ 125/250 VAC; 3 amps @ 480 VAC (Class A or H Limit Switch)
Wetted Parts: Stainless Steel process fitting and diaphragm and die cast aluminum enclosure.
Electrical Connections: Screw Terminals via conduit connection.
Pressure Connection is 1/4 inch NPT female (1/2 inch optional)
Enclosure Rating: NEMA 4, 7 & 9
Approvals: All models are UL and CSA listed for hazardous locations Class 1, Groups B,C,D and Class 2, Groups E, F, & G.  UL file # E37043.  CSA file is LR22354.
ATEX markings:
 EX models are ATEX marked as follows:
 0081, ISSeP 08 ATEX024X
 II 2G D, Ex d IIC T6
 Ex tD A21 IP66 T80°C

-40°C ≤ Tamb ≤ +75°C
Temperature Range is -40° to +165°F (-40° to +75°C)
Pressure Range: 0 to 150 PSI depending on model number.

Barksdale UL/CSA Listed Explosion-Proof Pressure Switch, D1XA3SS-UL, 1/4 inch SS NPT, .03 - 3.00 PSI

Barksdale UL/CSA Explosion-Proof Pressure Switch, D2XA3SS-UL, Dual Set, 1/4 inch SS NPT, .03 - 3.00 PSI

Barksdale UL/CSA  Explosion-Proof Pressure Switch, D1XH18SS-UL, 1/4 inch SS NPT, .40 - 18.00 PSI

Barksdale UL/CSA  Explosion-Proof Pressure Switch, D2XH18SS-UL, Dual Set, 1/4 inch SS NPT, .40 - 18.00 PSI

Barksdale UL/CSA  Explosion-Proof Pressure Switch, D1XA80SS-UL, 1/4 inch SS NPT, .50 - 80.00 PSI

Barksdale UL/CSA  Explosion-Proof Pressure Switch, D2XA80SS-UL, Dual Set 1/4 inch SS NPT, .50 - 80.00 PSI

Barksdale UL/CSA  Explosion-Proof Pressure Switch, D1XH150SS-UL, 1/4 inch SS NPT, 1.50 - 150.00 PSI

Barksdale UL/CSA  Explosion-Proof Pressure Switch, D2XH150SS-UL, Dual Set, 1/4 inch SS NPT, 1.50 - 150.0 PSI