1994 IIAR Technical Papers
  St. Louis, MO
 16th Annual Meeting

The Ozone Crisis and Business Opportunities for Ammonia
Author: Corin Millais

Now, we are increasingly focusing on the need for a dramatic shift by industry to the use of non-fluorocarbon ("not-in-kind") technologies. These solutions are the key to saving the ozone layer; ammonia is one of them. There are a wide number of these technologies in the marketplace, yet they have been denigrated, down played, and denied wider access due to the market dominance and untruths of the fluorocarbons industry, fearful of the threat to their potentially lucrative HCFC and HFC investments.
Process Hazard Analysis Made Simple: A Generic Approach
Author: P.J. Bellomo, Fred Dyke and Mike Kalfopoulos

The primary objective of this paper is to present the technical approach used to develop a generic Process Hazard Analysis (PHA) for ammonia refrigeration systems, based on a study conducted by Arthur D. Little, Inc. for the International Institute for Ammonia Refrigeration (IIAR) and the International Association of Refrigerated Warehouses (IARW). Both IIAR and IARW recognized that an ammonia refrigeration system is a process that can be addressed by what OSHA refers to as a "generic" PHA. A secondary objective of this paper is to offer a template for future generic PHA endeavors. It was concluded that the same technical approach used for developing a generic ammonia refrigeration system PHA can be readily applied to other systems. The paper will review the study conducted for IIAR and IARW, including: background, study scope, OSHA citation activity, philosophy of the work, and the generic approach developed.
EPA's Risk Management Plan Requirements
Author: Peter R. Jordan and Neil P. Mulvey

For the past two years, companies that own and operate ammonia refrigeration systems have been developing and implementing programs and procedures to comply with the Occupational Safety and Health Administration (OSHA) Process Safety Management (PSM) regulations. On October 20, 1993, the U.S. Environmental Protection Agency (EPA) published their long anticipated proposed regulations for Risk Management Programs for Chemical Accidental Release Prevention. On the whole, the proposed EPA requirements are very similar to the existing OSHA PSM regulations. However, the differences between the regulations are quite significant. Key differences include the need to conduct dispersion and consequence analysis and to make Risk Management Plans (RMPs) publicly available. This paper will describe the differences between the two process safety regulations, review the new EPA requirements in detail, and provide guidance on what ammonia refrigeration companies can do to prepare for EPA’s RMP requirements.
Risk-Evaluation of Ammonia when used as a Refrigerant
Author: Anders Lindborg

This presentation will highlight some important arguments for some of the common misconceptions about ammonia. Most opinions about ammonia are founded on myth, misunderstanding or, above all, ignorance. We must look at ammonia risk-evaluations based on: Refrigeration systems, disregarding other applications; Risk evaluation based both on the consequence of, and the probability or frequency for, an accident; Emission from the refrigeration system, with the parts of the system, where spills and ammonia vapor are in a building; and The need for qualified personnel to design, work with and assess refrigeration systems.
Ammonia in Ships
Author: Andrew C. Stera

As a result of the joint effort of the ship owner, shipyard refrigeration contractor, and Classification Society, in response to the present environmental issue, ammonia has found its way back into marine cargo installations somewhat earlier than expected. It disappeared from new reefer vessels about 25 years ago, due to some shipping companies' bad experiences with ammonia and the unjustified adverse publicity that ammonia received at the time the so-called safety refrigerant HCFC-22, now on the list of restricted substances, was first marketed.
Air Conditioning with Ammonia
Author: Steven J. Toth

Because of the problems with CFC’s, replacement refrigerants are needed for air conditioning. This paper demonstrates how ammonia, one of the oldest and most efficient refrigerants, is being used for air conditioning. With the right design and appropriate safety conditions/precautions, air conditioning with ammonia is the ideal solution! 
Variable Humidity for Vegetable Cold Storage
Author: Walter Gameiro

This paper shows that it is quite possible to design a cold storage plant that ranges in temperatures and relative humidities from 24F and 65% relative humidity for storing Chinese garlic to 58F and 95% relative humidity for storing melons in a different season. This same facility can also store frozen products. Since we are capable of providing our clients with this flexibility, they no longer need to use the cold storage for summer fruit only. Previously, many of these plants were closed for five or six months a year due to inflexible temperature control, which caused a low return on plant investment.
Defrosting Evaporators with Water
Author: George C. Briley, P.E. and Thomas A. Lyons, P.E.

There are a number of advantages for water defrost systems. These advantages include: The energy required for water defrost is less than for hot gas defrost. The only loads added to the refrigeration system are those required to return the coil to operating temperature and the losses to the surrounding area. This energy cost will vary with the application. Water defrost keeps coils clean except in very dirty applications (IQF Vegetable Freezers). If a refrigerant leak exists in a room where water defrost is used, stop the refrigerant flow to the unit; shut off the fans; and open the water defrost valve. The water will absorb the ammonia very rapidly. Caution: the water from the defrost may have to be diluted before it is discharged into a sewer. Water defrost, combined with hot gas defrost, can be employed where extremely rapid defrost is required.
Demand Defrost ... Does it Work?
Author: Norman Hockler

This paper poses the question that "if demand defrost is a good idea, why are most coils defrosted by time?" If you were to ask your contemporaries whether or not they have used demand defrost, you may hear: "I tried it and it doesn't work", or, "I heard it doesn't work." Rarely will someone say "Yes, it works great and it has saved me a bundle of money." Saving money is something we all would like to do, especially in this time of proposed higher utility rates. One thing we all do know is that utility rates are not going to come down. The object of a demand defrost system is to reduce energy usage, which results in saving money. Do demand defrost systems work? The answer is both yes and no. Like everything else, some demand defrost systems work and some do not; this paper discusses the various reasons why. A successful demand defrost system depends on precise identification that a defrost is needed immediately. 
Practical Design Tips for Plate Heat Exchangers in Ammonia Refrigeration Systems
Author: Steven M. Wand

In the last several years, significant changes have been occurring in refrigeration heat exchanger technology. These changes offer new applications, improvements in ammonia refrigeration performance, and lower equipment costs. The changes also allow ammonia refrigeration systems to be more affordable to smaller users and more competitive with halocarbon systems. This paper highlights the characteristics of plate heat exchangers compared to traditional shell and tube heat exchangers. The paper further provides some "Practical Design Tips" to apply plate heat exchangers to ammonia refrigeration systems.
Plate Heat Exchangers as Liquid Cooling Evaporators in Ammonia Refrigeration Systems
Author: Michael A. Young

This paper will outline the construction of a plate and frame heat exchanger, illustrate the benefits, and describe how they are installed in refrigeration systems as liquid cooling evaporators. Small capacity (1 /4 to 30 tons) nickel or copper brazed plate heat exchangers are available for refrigeration, but are not included in the scope of this paper.
Taking Advantage of the Screw Compressor Side Port
Author:  Rudy Stegmann, P.E.

Screw compressors, because of their geometric construction, operate with a fixed internal volume ratio. Regardless of the imposed system pressures, the gas within the compressor will gradually compress from the suction level as it traverses the screws until it reaches the discharge port. Here, its compressed volume is a function of the absolute suction pressure and the specific Vi (volume ratio or index) of the compressor. Vi is defined as the ratio of the volume of vapor in the screw cavity at suction port closure to the volume of vapor in the cavity when the discharge port is uncovered. The pressure at this point may be less than, equal to, or above the system condensing pressure. This gradual pressure increase within the screw compressor permits access to be made at any position along the screw and at any corresponding pressure level. Introduction of additional vapor into the compressor can be made at this access. This paper will discuss the utilization of this access known as the Side Port for the purpose of providing liquid subcooling and as a second compressor suction port for a higher temperature evaporator load.
Proper Selection and Application of Centrifugal Liquid Overfeed Pumps
Author: Rob O'Brien and William Carnes, P.E.

This paper discusses the proper selection and application of centrifugal liquid overfeed pumps and the system parameters leading up to that selection. It will also cover the determination of system flow and pressure requirements, the evaluation of net positive suction head, the recommendations for piping considerations, reading typical performance curves, the impact on pumps during a decrease in system pressure, and troubleshooting.
Using Low Pressure Receivers
Author: William V. Richards and Thomas L. Cooper

The functions of a Low Pressure Receiver are to: (1) separate liquid from overfeed return suction vapor; (2) provide liquid ballast to accommodate operational changes in liquid requirements in the plant; and (3) provide liquid holding or surge volume for the largest pump required during operation, service, or standby, without causing liquid to carry over to the compressor.
Capacitance Level Probes for Refrigerants
Author: John A. Yencho

Liquid level controls for refrigeration have been primarily used in industrial and large commercial systems, especially where evaporators are flooded rather than directly expanded. Due to environmental considerations and the increasing cost of refrigerants, more complete measurement and monitoring of refrigerant liquid levels in various sections of the system are being implemented. Systems no longer should contain excessive reserve amounts of refrigerant; this will require early detection of refrigerant inadequacy due to losses or system changes. Other fluids and applications are discussed in brief detail to introduce other possible applications associated with our industry. To help understand where and how liquid refrigerant capacitance level probes might be used, this paper discusses previous types of level controls, and examines some of the common applications. The construction of the probes is also briefly reviewed.
Ammonia Sensors for Refrigeration Applications
Author: Horacio Perez-Blanco and Wilbert F. Stoecker

The need for reliable ammonia sensors for leak detection and personnel protection is of great importance to the field of industrial refrigeration. The present work is aimed at identifying existing sensors and at defining their detection capabilities. The working principles of present day sensors are outlined. Measuring ranges, selectivity, and calibration needs are evaluated for most of the sensors described. In this way, a concise, yet comprehensive guide, for sensor selection is developed. Advanced sensors, such as fiber optics and ammonia-sensitive gates for FETs, are discussed, and their potential for improving ammonia detection is outlined.
Safety and the Contractor -- A Different Angle --
Author: Larry Cleary

In the process of complying with the deluge of safety rules and regulations enacted in recent years by federal, state and local agencies, contractors often overlook the positive aspects of initiating and maintaining a good personnel safety program. We probably would all agree that proper attention to safety has always had a positive impact on our businesses and our industry, regardless of all the new rules and mandates. It is not the intention of this paper to review all the new safety regulations, but to present the concept of safety and the contractor from a different angle. The development and enactment of a sound and functional safety program will assist contractors in achieving a most important goal -- profitability. Rather than considering safety regulations as yet another burden imposed by the government to make life more difficult, contractors can use safety as a tool to increase their profitability.
Refrigeration Pipe Welding Procedures and Qualifications
Author: Henry A. Saye, P.E.

Owners of ammonia industrial refrigeration systems and their installing contractors want the systems to be installed safely and according to the recommendations and requirements of various governing bodies. Numerous organizations, such as the International Institute of Ammonia Refrigeration (IIAR) and the American Society of Mechanical Engineers (ASME) provide installation guidelines and instructions. This paper deals specifically with the installation of refrigeration piping, and particularly with pipe welding procedures and qualification of welder performance.