Common problems with installation

Experience has shown that it is very easy for gas protection measures to be installed incorrectly or for them to be damaged after installation by follow on trades (plumbers, electricians etc.). Independent inspection and QA procedures are therefore vital when installing gas protection. Common problems in the installation of protection in housing have discussed in BRE Report 414 (Johnson, 1999) and in the latest NHBC guidance on ground gas (Boyle and Witherington, 2007). 

Testing of membranes for leaks can increase confidence in the installation but independent installation should still be required. Experience has shown that even quality assured and tested membranes can suffer damage after installation and approval. Examples of damage to membranes or poor installation that has been observed are simraiarised below  

Follow on trades often cause damage to exposed membranes. The membranes should therefore be protected after laying (there are proprietary boards or geotextile fleeces available for this purpose) or ffie membrane should be inspected immediately before it is covered over, especially if it is in a housing development where plumbers, plasterboarders etc. have been working over the membrane. 

As a final illustration of why validation is so important some quotes from engineers that undertake this kind of work are provided in Box 9.1. 

1 Quotes from consulting engineers who validate membrane installation 

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Another common problem with orifice meters is having the wrong plate in the meter. That is, the calibration of the meter was done assuming a certain size orifice however, a different size plate was installed. This may seem silly, but it is a frequent occurrence and is usually difficult to detect. 

Cation exchangers are regenerated with mineral acids when used in the form. Sulfuric acid [8014-95-7] is preferred over hydrochloric acid [7647-01-0], HCl, in many countries because it is less expensive and less corrosive. However, the use of hydrochloric acid is the best method of overcoming precipitation problems in installations which deionize water with high concentrations of barium or calcium compared to other cations. A 4% acid concentration is common, although sulfuric acid regenerations may start as low as 0.8—1% to minimize calcium sulfate [7718-18-9] precipitation. 

Piping gaskets with undersized IDs installed, a very common problem in small pumps. 

One of the more common problems associated with baghouses is improper installation of filter media. Therefore, it is important to follow the instmctions provided by the vendor. If the filter bags are not properly installed and sealed, overall efficiency and effectiveness are significantly reduced. 

Thermocouples and wire leads require constant maintenance due to wire breaks and malfunctioning thermocouples. In most cases, the root cause of the problem is easy to determine. When a thermocouple loses continuity the instrument panel typically reports either an open circuit or a very negative temperature. A more difficult but also common problem occurs when the control thermocouple is not located close to the heating element on the control system. In this case, it is possible for the thermocouple to be influenced by another heated control zone while allowing its control zone to operate at temperatures that can be either very hot or very cold. Such cold conditions can cause the polymer to solidify in the transfer line while a hot condition can cause the resin to degrade. During the installation and startup of new equipment, it is important that the thermocouples are matched with the proper controller and control zone. 

A calibration check of controllers should be made on a regular basis. The ISO 9000 standard reviews developing the frequency calibration checks. A visual examination should be made before proceeding with the check to determine that no damage exists. Some of the more common problems caused by a plant s hostile environment that can effect equipment such as sensors/transducers are noise interference, mounting holes (must be concentric and clean), installation, diaphragm considerations, and transducer calibration. Zero balance, full-scale sensitivity, and R-cal at 80% parameter reference points for calibration can be used. The sensor/transducer manufacturer provides these parameters.154... 

To obtain a high selectivity, i.e., discrimination between the analytes and various unwanted matrix compounds, membrane extraction has a clear advantage over other sample preparation techniques, as all compounds that reach the analytical instalment must travel through the membrane. There is no direct connection and possibility for transferring compounds into the analytical instmment in other ways. This is not the case with other extraction techniques. With SPE, SPME, etc., there is a definite possibUity that matrix components are absorbed on the sorbing phase and subsequently being eluted into the extract. With LEE, such a transfer is less probable and it is generally considered that extracts after LLE are cleaner. The possible and common problem of the formation of emulsions at the phase interface with LLE, which is avoided with aU types of membrane extraction, is a source of contamination across the phase border. 

Aseptic Assembly. The first interventions performed are those that prepare the equipment for the aseptic process. This entails the removal of sterilized materials and equipment items from the autoclave and transfer to the location where the aseptic processing activities will be performed. This is ordinarily followed by the assembly/preparation of the equipment for the process. Aseptic assembly in which sterilized parts are removed from protective materials, installed and adjusted in preparation for the aseptic process are perhaps the most potentially invasive of all of the activities which must be performed. The operator must be meticulous in their execution of these tasks to prevent the inadvertent contamination of product contact surfaces. Strict adherence to the principles of aseptic technique described earlier is essential. These interventions are a necessary part of every aseptic activity, and it is common to identify the first containers filled as they may be more indicative of potential problems with the aseptic assembly. For this reason, the validation program should include process simulations that include containers filled immediately after the set-up of the equipment. 

Setting up a low-temperature x-ray laboratory requires a certain investment of resources, and without a serious commitment the results are likely to be disappointing. Unfortunately, one cannot expect all cooling units to perform well as delivered by the vendor, although at least the more commonly sold models are basically sound. Up to this time the real responsibility for good performance has been left with the customer. Common problems are proneness to icing, excessive coolant consumption, and inadequate temperature stability. Solutions to the problems depend on model and make, and are beyond the scope of this book. Many unnecessary difficulties can be avoided by seeking advice from laboratories with successful low-temperature installations. 

A common problem to do with the writing of procedures is that the activity is not treated as a project in the same way as say the purchase and installation of a new piece of equipment would be. All too often technicians, supervisors, and engineers are asked to write the procedures as time permits. Yet the writing of a manual normally requires a considerable amount of time and money. 

Balance ropes may not behave satisfactorily in very deep shafts, due perhaps to the dynamic behavior of the ropes causing tangling of the rope loops at shaft bottom or other unforeseen problems. In some mining jurisdictions it has been common practice to employ sheaves at the shaft bottom to control the balance rope loops, and the deepest existing Koepe hoist installations employ these balance rope sheaves. This adds additional costs and complexity and may not be of any value. Simulations or tests may be required to identify any problems with balance ropes for deep shafts. 

It is important to know that steam traps should not be sized based on pipe size. A common problem is poorly sized traps that cause premature failure through excessive cycles and wear on internal parts as well as excessive steam leaks. Therefore, steam traps are selected primarily on duty second, on duty variation for transient cases and third, on equipment requirement (Kenny, 1989). Proper installation and maintenance together with regular vendor service can maintain good steam trap performance and long life. 

Commonly referred to as splash type holders, these are used primarily in side mounted installations where accessibility is easy. They are insensitive to slightly contaminated water, but there are frequent problems with water drainage and electrode corrosion. In addition, they use... 

The majority of industrial slurry-transport installations tend to be free of cavitation and related problems with pump suction performance, but in many other applications cavitation is important and must be considered in system design. In disposal pipelines operated by the dredging industry and also in pipeline applications such as those used by the phosphate extraction industry (for example in Florida, U.S.A.), the first (upstream) pump is susceptible to highly sub-atmospheric suction pressures (see Fig. 1). In these cases, cavitation is a common occurrence, and may be significant in determining the costs of operation. 

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