New at PipingDesign.com: 31 January 2001

[Process-Cooling.com is a great reference site (as evidenced by all the links from there below), it's probably worth it to just go there and surf around a bit]

<a href="http://www.pipingdesign.com/insulation.html">http://www.pipingdesign.com/insulation.html</a>

How to Maintain Liquid Cryogen Quality
Process-Cooling.com

<<Liquid cryogens normally exist as a two-phase fluid - a mix of
liquid and gas. Liquid cryogen quality refers to the ratio of liquid cryogen within the two-phase cryogenic fluid. A higher percentage of liquid results in a higher quality cryogenic fluid as well as higher cooling capacity per pound of fluid. Consequently, cryogenic liquid quality is an important factor when designing a cryogenic piping system for process cooling. One way to maintain high quality is to minimize heat leak into the piping system. This is best accomplished with vacuum-insulated, multilayer insulation. However, certain applications require a higher quality liquid than a vacuum-insulated piping system alone is able to deliver.>>

Comparing Cryogenic System Operating Costs Process-Cooling.com
(Relocated from Practical Piping Design page)

<<Cryogenic piping system design is dependent upon the system's
application and operating characteristics. When selecting a pipe insulating system for cryogenic applications, base your decision upon the application's operating characteristics, and keep in mind how usage pattern can affect your insulating system choice. Key operating factors to consider include: cryogenic fluid flow rate, fluid type, usage pattern or cycle time of the cooling application, required liquid quality, distance from the liquid storage point to the use point. Cryogenic applications can be segmented into four general categories: high flow continuous operation, low flow continuous operation, high flow intermittent operation and low flow intermittent operation. To determine each category's most efficient insulating system, the designer must calculate the system's total cooling losses. This total includes the initial cooldown losses to chill the process pipe to cryogenic temperature plus the steady-state heat leak into the piping system.>>

<a href="http://www.pipingdesign.com/pumps.html">http://www.pipingdesign.com/pumps.html</a>

Select A Positive Displacement Pump In 10 Steps Viking Pump, Inc.

<<The following article is an abbreviated version of Viking Pump's
PD pump selection process and discusses how and why certain application data is utilized during the selection process. The specific mathematical calculations for each step are beyond the scope of this overview but warrant discussion in future articles -- in fact, each step of the process contains enough information to be an article unto itself. And although this is the Viking Pump selection process, the basic steps and data requirements are similar for all PD pump manufacturers.>>

<a href="http://www.pipingdesign.com/exchangers.html">http://www.pipingdesign.com/exchangers.html</a>

Fundamentals of Cooling Tower Design & Optimization ProcessCooling.com

<<Your cooling tower may be the most overlooked piece of equipment
at your facility. A cooling tower uses a combination of heat and mass transfer to cool process water. If improperly selected or poorly maintained, it will cost you financially, causing a loss in production due to increases in circulation water temperature and increased electrical operating costs. Emphasis must be placed on properly specified and designed cooling towers that require minimal maintenance. Cooling towers come in all shapes and sizes. Cooling towers with fans are referred to as mechanical draft - forced or induced draft, depending on fan location. Some cooling towers, used primarily in the utility industry, operate on a natural draft chimney principle without any fans. As their name implies, cooling towers employing this design are referred to as natural draft. >>

Heat Exchanger Design Q & A
ProcessCooling.com

<<Heat exchanger manufacturers need answers to a number of
questions to correctly size a heat exchanger for a specific application. The questions attempt to address the three basic points that drive heat exchanger design: Why a heat exchanger is needed, what the exchanger needs to do, how the exchanger can do the job. >>

<a href="http://www.pipingdesign.com/designpractical.html">http://www.pipingdesign.com/designpractical.html</a>

How to Dose Liquid Nitrogen Effectively (Liquid Nitrogen Piping) Process-Cooling.com

<<Liquid nitrogen piping must have some insulation to effectively
transfer the liquid nitrogen with minimal vaporization or loss. There are two types of liquid nitrogen piping: vacuum jacketed and nonvacuum jacketed. Vacuum-jacketed lines are more efficient than unjacketed lines and operate frost-free. A vacuum jacket is an annulus positioned around the inner liquid nitrogen pipe. The evacuated annulus reduces the conduction and convection heat losses to extremely low levels, creating efficient inner liquid nitrogen pipe insulation. Dynamically pumped and static vacuum are types of vacuum-jacketed lines. Static vacuum lines typically are evacuated by the manufacturer and sealed off for vacuum integrity. This vacuum eventually will degrade, resulting in increased heat losses and decreased performance over time. Dynamically pumped lines utilize a vacuum pump on the vacuum annulus. The vacuum pump must run continuously, which adds slightly to operating costs. However, vacuum integrity will improve with time and last for years. Jacketed lines can be either rigid or flexible pipes. Rigid pipes must be accurately dimensioned for proper installation into a facility, whereas flexible lines are easier to install and allow more versatile routing. By contrast, unjacketed lines typically are foam insulated and have a heat loss as much as 20 times greater than that of a jacketed line. They also have a larger outside diameter than jacketed lines. Foam-insulated lines typically lose their insulating qualities as the foam degrades over time. >>

Choosing Your Cryogenic Piping System
Process-Cooling.com

<<"What piping system do I use?" This is the most frequently asked
question by companies installing cryogenic systems for cooling and freezing applications. The answer is: There is no one right answer. The choice is driven by the total system cost, which includes the initial installation expenses plus the ongoing operating and maintenance costs. Installation costs usually are straightforward to obtain, but operating costs are more complicated. The most significant operating cost is the loss of cooling capacity of the cryogenic fluid. Cryogenic fluids are stored at or below -300°F (-184°C) while the ambient temperature around the cryogenic system can be more than 100°F (38°C). This temperature difference causes a significant amount of heat to enter the cryogenic fluid, reducing its cooling capacity. As a result, more cryogenic fluid is required to cool the process and operating costs increase. An insulated piping system can reduce these operating costs by minimizing the amount of heat that reaches the cryogenic fluid. >>

"New bridge crack detected"
<a href="http://www.mmsd.com/images/hoan56.rm">http://www.mmsd.com/images/hoan56.rm</a> (From http://www.mmsd.com/) Received on Wed Jan 31 10:54:00 2001