Gritton & Associates » Technical

Why use HDPE in cooling tower construction?

admin — Thu, 06 May 2010 22:30:48 +0000

Corrosion Resistance . . . High Density Polyethylene (HDPE) is the optimum material for cooling tower construction. The material is molded into a totally seamless shell, which will never leak, unlike conventional cooling towers which require many panels, joints, seams, seam gaskets, caulking and hundreds of bolts or other fasteners to maintain the integrity of the product. The Delta structural shell will never rust, chip, crack or ever need painting or further protective coatings. The structural shell is warranted for 15 years which is much longer than other available cooling towers.

Galvanized steel towers provide only interim corrosion protection. The zinc galvanizing is designed only to delay corrosion as the zinc wears steadily away. Moderately high temperatures and various water chemical treatments speed up this leaching of zinc into the water or atmosphere. With only ounces per square foot of corrosion protection, it is only a matter of time till corrosion of the underlying sheet steel sets in.

Thin fiberglass panels can also not match the structural integrity of Delta’s seamless engineered plastic. Over time leaks can develop at the joints even with gaskets and caulking applied. Thin fiberglass when exposed to the wide range of outdoor weather elements is also subject to delaminating, wicking and overall degradation

Selecting a Fan Array System for an Air Handling Unit

admin — Mon, 14 Dec 2009 17:49:52 +0000

This is a great paper that discusses key topics involved in selecting a fan array system. Topics discussed in this paper include

VFD Considerations and Electrical Requirements
Sound and Efficiency Considerations
Vibration
Space Considerations
Reliability
Seviceablity
Cost
Fan Array System Options

Download White Paper

How Hydronic System Components Really Work

admin — Wed, 09 Dec 2009 17:39:21 +0000

This is an article written by Bell & Gossett for Oil Heating Magazine. It goes into detail about the components of a hydronic system and discusses how they work. A must read for anyone interested in understanding the basics of hydronic system design.

Click Here to read more

Examining Causes of Pump Vibration as Featured in HPAC Engineering

admin — Thu, 03 Dec 2009 18:53:30 +0000

Many vibration problems are a result of interactions among a system’s pump, motor, fluid, piping, and structure. This interactive relationship requires a systems approach to vibration analysis, rather than the investigation of individual components. This article discusses the cause of vibration, how is it measured and described, its limitations, and many other vibration related issues. Click here to learn more.

ESP-Plus: Spotlight on Pump Curves

admin — Thu, 03 Dec 2009 18:49:23 +0000

Not all pump selection programs are created equally. The algorithms used to select pumps and generate curves need to be very sophisticated. ESP-PLUS® uses a three curve interpolation method developed by ITT. Unlike some other pump selection programs on the market, you can be assured the results from ESP-PLUS are very accurate. Visit ESP-Plus Online

Manifolding Condensate Return Vent Lines

admin — Thu, 03 Dec 2009 18:45:00 +0000

We are often asked if it is necessary to run separate vent lines for each condensate return unit in a multiple unit system. Large systems or multi-zone systems often make individual venting impractical. There are no industry standards for sizing condensate return vent manifolds, but ASME Controls and Safety Devices for Automatically Fired Boilers (CSD-1) guidelines for manifolding gas pressure relief valves can safely be applied. click here to learn more.

ESP-Plus: Sizing an Expansion Tank

admin — Thu, 03 Dec 2009 18:38:50 +0000

When Bell & Gossett redesigned the ESP-PLUS® tank selection program a few years ago, they sought comments from users about the program. The feedback came back in two camps. One group wanted a simpler program where the engineer could just enter the basic sizing parameters like other manufacturers’ programs. The other group wanted even more design help than offered in the existing ESP-PLUS program. Our solution? Offer both.

Direct Sizing Method

If the engineer knows the tank sizing parameters, he or she can enter them using the direct sizing method. Users who need more guidance in calculating the parameters can choose one of several methods that match their system type. In ESP-Plus, each system type shows a sample system schematic to help the user answer questions that will lead to a proper tank size. Each of the tank sizing parameters has a help option that guides the user. In addition to tank sizing, you can size any of the hydronic equipment by clicking on that item in the schematic. ESP-Plus gives you the ability to spec out the entire system including the tank, pressure reducing valve, pressure relief valve, air separator and the new tank purge valve.

Estimating System Volume

If the user doesn’t know the total system volume – a required input for tank sizing – ESP-Plus offers two methods for estimating the total: Component and Chiller Size. The component method works by entering the water volume for different system components. ESP-Plus includes calculators to help. As an example, for pipe, a calculator allows you to enter the total length of each of the different pipe diameters.

After the user clicks on the ‘Size Tanks’ button, ESP-Plus will display all the possible tank selections and show their cost ranking. Information screens are available to describe the features of each of the different tank types. When sizing a new diaphragm or bladder type expansion tank to replace an old compression tank, use the ESP-Plus program to simplify the process. Just input all of the requisite information – system size, pressure, etc., and ESP-Plus will help make the selection. And, once you install the new tank, make sure you properly dispose of the old compression tank.

A final report is available that shows each of the components for the air control system. The report includes the proper field settings for tank and fill valve pressures and links to product information and CAD drawings.

For a free copy of ESP-Plus contact Gritton & Associates

Hot Water Recirculation in High Rise Buildings

admin — Thu, 03 Dec 2009 18:35:51 +0000

“A growing trend and buzzword in the industry is the emphasis on turning, ‘Green’.” Traditional methods of hot water recirculation are being applied to high rise building systems in order to decrease the unnecessary “dumping” of cold water, and the resulting convenience coupled with water savings, both offer significant benefits to the user. An alternative method that can offer greater savings and increased efficiency is to “decouple” the recirculation loop. To read more about the alternative design method and its benefits click here.