SUSTAINABLE ENERGY
calibrate your full range of equipment, that equates to five different purchase orders and five different invoices that need to be processed – all of which can add to your cost base.
5: Don’t settle for speed over accuracy
Fast turnarounds are not everything. Quality of measurement is more important and should never be compromised for speed. The fact of the matter is, high level measurement takes time and certain equipment, such as dimensional test equipment needs time to stabilise to the right temperature, sometimes several hours. This is especially important for on-site calibration where mobile laboratories may not have the same level of environmental control as a permanent facility. A calibration laboratory that sells its services purely on the basis of speed could be cutting corners.
6: Review your supplier’s accreditations
Accreditations are important and customers should ask to see them. From a technical point of view ISO9000 certification is not enough. It does prove that the company has a Quality management system in place, but the audits do not go into the technical competence of the laboratory. An ISO 17025:2005 accreditation proves that an independent body, such as UKAS has inspected the laboratory and assessed its calibration techniques, procedures and engineer competence for a specific capability. All UKAS Schedules are available to view on line at
www.ukas.com
7: Ask about the full range of capability
It is not always cost effective for a calibration laboratory to invest in the equipment or expertise for a full capability in all types of instrument calibration and some quite rightly focus on a particular area of expertise. However some companies may offer an extensive range of calibration services, but when you examine the range of a particular parameter you could find that their capability in this field, and therefore the calibration service that they can provide, is very limited. Ask what your supplier does when a piece of equipment comes in for calibration outside their normal area of expertise.
8: Ensure your equipment is calibrated against its full specification
Sometimes equipment can be calibrated and customers told that it is “compliant” with the original OEM’s specifications, but the calibration has not tested the limits of the specification only the mid-range where it often has a better chance of passing. In the past, at Trescal, we have failed equipment because it does not reach its full published specification which has resulted in changes to a manufacturer’s data sheets. The bottom line is that for end user confidence, equipment needs to be compliant across its full specification unless otherwise agreed and stated on the certificate.
9. Ensure that any measurements are “traceable to national standards”
In order to ensure that measurements are equal worldwide, a system of international and national standards exist. Calibration companies must be able to prove that their own standards are traceable to national standards through a series of comparisons. Check the certificate and ensure that it contains information about the traceability of measurement so that you can prove your own traceability
10: Look out for the added-value services
Low prices will usually mean a streamlined service, but this will mean that you miss out on the added-value services which could ultimately save you money. Free collection and delivery and free asset management are just two of the services which often get bundled into the calibration price and offer customers the opportunity to take cost out of their business. For a customer with a large pool of equipment there is huge potential to save time and money internally by using an external asset management service, particularly if it comes as part of a calibration package. Above all, don’t be afraid to ask difficult
questions. Defensive or muddled answers should set alarm bells ringing.
Stephen Cain
UK & Group Communication Coordinator Tel: 01252 533 317
E-mail:
Stephen.cain@
trescal.com PLATE HEAT
EXCHANGERS FOR
COMMERCIAL APPLICATIONS
A
hot water system using a plate heat exchanger (PHE) does not store hot water. The water is heated instantaneously and only
when required, so it is intrinsically energy efficient. A hot water system using a plate heat exchanger (PHE) does not store hot water. The water is heated instantaneously and only when required, so it is intrinsically energy efficient. A PHE consists of a pack of plates (usually stainless steel) to transfer heat from the primary fluid to the secondary fluid. The plates and gaskets are arranged to form alternating channels between the primary and secondary fluids. Arranged in this way the plates have an extremely large heat transfer surface area and therefore considerably high loads are achieved from a very compact plate heat exchanger. For large commercial applications a PHE is ideal as it is capable of producing hot water instantly and constantly at peak times. Calorifiers and direct-fired water heaters are less reliable and can empty of hot water should higher than normal demands occur.
Plate heat exchangers are easy to
maintain. An engineer can usually strip, clean and re-assemble a typical unit within an hour, and they are easy to keep clean. Because they are non-storage units, PHEs present no risk of contamination of the water with legionella microbes. The water is heated instantly on demand, and therefore the bacteria, which thrive in wet environments at temperatures between about 20 and 50 deg C, have no chance to breed.
For further information on Stokvis plate heat exchangers, call 020 8783 3050 or visit
www.stokvisboilers.com
PSS MAGAZINE • NOVEMBER/DECEMBER 2015
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