Consultancy and Testing
Critical Facilities Solutions offers independent consultancy services on Data Center contamination management and control in four main areas: Initial Design Phase; Construction, Building and Fit-Out Phase; Live Data Center’s and Environmental Assessment and Testing.
Our consultants have over 20 years experience (each) in the design, construction and management of critical environments and specifically Data Centers. They have first hand experience on cooling, flooring, racks, containment and the overall environment. This places them in an extremely advantages position to advise our customers on what steps should be taken to meet best practice. It also uniquely positions them to investigate any issues or problems with contamination and advice on the appropriate course of action.
Testing & Consultancy Services Include:
- Indoor Air Quality Testing and Certification (ISO14644-1)
- Indoor Surface Cleanliness Testing and Certification (ISO14644-9)
- Contamination Collection, Lab Sampling
- Source Detection
- Compliance Verification
Where a 3rd party has completed cleaning actives CFS will independently inspect, test and certify the clean and issue a detailed report.
- Post Clean Audits
Where a 3rd party has completed cleaning actives CFS inspect and issue a detailed report.
- ‘White Glove’ Inspections and Reporting
CFS offer Data Center tenants a service whereby we inspect the Colocation Data Center for cleanliness and air quality prior to you installing your equipment into the facility.
Zinc Whisker Management, Testing and Consultancy
Why Zinc Whiskers Remediation is so Important
Zinc whiskers are a serious threat that can grow in Data Center’s and WILL cause hardware failures. Critical Facilities Solutions Zinc Whisker Testing & Consultancy services assure its clients a Data Center that is either free of zinc whiskers, or one that is professionally managed thereby eliminating many potential data corruption and server performance problems in the process. While there is no permanent ‘cure’ for Zinc Whiskers besides a full blown replacement of all effected parts, CFS will extract the majority of the longer dangerous zinc whiskers that threaten your systems with a report and management plan on completion or a full certification, if none are found, from CFS.
Formation and Characteristics
Zinc whiskers are a phenomenon that can occur on bare metal surfaces. Metal surfaces are coated with zinc in a galvanisation process to help protect them from corrosion. While several techniques are used, such as hot-dip or spraying, whisker growth appears to be limited to electroplated samples. The whiskers are zinc crystals formed by the degradation (corrosion) of the galvanised metal surface. Several industry studies have shown that whisker growth is dependent on internal stresses during the plating process. The crystalline structure within the metal will attempt to relieve the internal stress by enlarging the structure through the growth of crystals. The growth path is outward and the material is literally pushed out of the surface of the metal.
These crystalline growths (whiskers) are typically 2 microns in diameter and over time (many years) can grow to be several millimetres in length, up to 10mm although typically <1mm. Under proper lighting, they can be visible to the naked eye on surfaces. The whisker formation process consists of an unpredictable incubation period, typically lasting months or even years without any growth at all, followed by a period of growth at rates as high as 1mm per year. Some zinc coated surfaces may never grow whiskers. Unfortunately, accelerated techniques do not currently exist to predict if, when, and to what extent a zinc-coated surface will produce whiskers.
Effects of Zinc Whiskers: System Failures
While whiskers remain attached to their source ie floor panel, pedestal etc they are basically benign, however when the whiskers are disturbed and dislodged they become airborne and circulate freely throughout the environment. Disturbance is likely to be caused by routine maintenance activities in a Data Center, including lifting, sliding and reinstalling of access floor tiles and the pulling of electrical cable in the subfloor space. For efficient cooling the forced air-system typically pressurises the subfloor space with chilled air. Perforated floor tiles and air vents provide channels through which the cool air, including the zinc whiskers, can pass into the above floor space. Ultimately many whiskers can pass into the electronic hardware through vents and fans on the equipment. Once inside the equipment zinc whiskers, which are electrically conductive structures, can cause various electrical failures, ranging from intermittent to permanent short circuits. Whisker debris can also become a physical impediment to moving parts or obscure optical surfaces and sensors within some equipment (such as disk or tape drives) The first identification of zinc whiskers, and its associated system failures, occurred in the 1940’s. Renewed interest has arisen triggered by the apparent increase in reported failures. Several factors appear to contribute to the apparent increase:
- Continuous miniaturisation of electronic components technological advances have led to more densely packed circuitry and tighter spacing between conductors, therefore smaller conductive particles can now cause shorts.
- Reduction in circuit voltages and currents newer systems operate at lower levels and therefore energy from these components may not be sufficient to melt a zinc whisker, resulting in increased risk for permanent shorts.
- Age of existing floor structures many facilities now have flooring that has been in place for in excess of 10 years thus whiskers are of a length capable of bridging exposed conductor spacing’s.
- Increased maintenance and up-grade activity in raised-floor facilities any activity that involves moving flooring can dislodge whiskers, in today’s high-tech environments it is more commonplace for computing facilities to undergo regular maintenance activity, ie adding, removing hardware, repositioning and reconfiguring equipment etc.
During a one-month period, a NASA Data Center experienced at least 18 catastrophic power supply failures in newly installed mass memory storage devices. The ensuing failure investigation determined that the causes of failure were electrical short circuits’ These had been caused by small metallic filaments growing on the underside of raised floor tiles and support structures that had been dislodged during maintenance and distributed throughout the Data Center by forced air cooling systems.
Indoor Air Quality Testing (ISO14644-1)
Critical Facilities Solutions test each room to confirm the level of air quality against the Cleanroom Class DIN EN ISO 14644-1 standard for Cleanrooms and machine rooms which encompasses Data Center’s. The tests are done using a calibrated air particle counter. Critical Facilities Solutions aims to confirm that the Data Center and each room within it meets the minimum IS Class 8 for Data Center’s as per OEM best practice guidelines. A single Air Particle Count or Indoor Air Quality Test (IAQT) measures the volume of airborne particulate within one cubic meter (1m3) of air within the room. The ISO standard requires that a number of test be taken at different positions in the room depending on the size and shape of the room. The sum of the results is then divided and the average is the volume per cubic meter for that room.
1. Using a hand held or static air particle machine that has been properly calibrated collect one (1) air sample per 25 square meters of room space. (I.e. in a 100 sqm room a minimum of four (4) tests should be taken.
- The location of each test should be documented and if you are looking to trend the air quality in a certain room future tests should be taken at the same location each time.
2. The particle machine should be at an elevated height of one (1) meter above the floor surface.
- The particle machine should remain static during the test.
- The machine should be set to complete each test over a one (1) minute (sixty (60) second) period.
- During the test the machine will draw in one (1) cubic meter of air for analysis.
3. The machine should be set to test particles at 0.5 microns for Class 7 & 8 and 0.3 micron for Class 5 & 6.
4. The results of each test should be recorded. (I.e. test 1 = 3,100,000; test 2 = 2,400,012; test 3 = 832,000 etc) these results should be added together (6,332,011) and then divided by the number of tests (3) to get an average for the room (2,110.670) which in this example is a Class 8.
5. ISO table to identify the class achieved:
Indoor Surface Cleanliness Testing (ISO14644-9)
Critical Facilities Solutions test surface areas against the Cleanroom Class DIN EN ISO 14644-9 standard for Cleanrooms and machine rooms which encompasses Data Center’s. The tests are done using a calibrated surface particle counter. Critical Facilities Solutions aims to confirm that the Data Center and each room within it meets best practice guidelines. A single Surface Cleanliness Test measures the volume of particulate within a certain sample area but agitating the surface to release the particles and then using the same machine as we use for IAQT to evaluate and count volume of particulate.
ISO 14644-9:2012 establishes the classification of cleanliness levels on solid surfaces by particle concentration in cleanrooms and associated controlled environment applications. ISO 14644-9:2012 applies to all solid surfaces in cleanrooms and associated controlled environments such as walls, ceilings, floors, working environments, tools, equipment and products. The surface particle cleanliness (SPC) classification is limited to particles between 0,05 µm and 500 µm.
The following issues are not considered:
- requirements for the cleanliness and suitability of surfaces for specific processes;
- procedures for the cleaning of surfaces;
- material characteristics;
- references to interactive bonding forces or generation processes that are usually time-dependent and process-dependent;
- selection and use of statistical methods for classification and testing;
- other characteristics of particles, such as electrostatic charge, ionic charges, microbiological state, etc.
Contamination Collection & Sampling
Critical Facilities Solutions undertake sample collection and gathering using specific methods dependent on type of analysis. The locations are documented and the samples collected into suitable containers to ensure no cross contamination. The samples are sent to an independent laboratory for analysis using the latest and most efficient methods for determining the composition of a sample such as XRF or SEM followed by recommendations, proposals and quotations together with a detailed program and plan for any remediation works.
XRF (X-ray fluorescence) is a non-destructive analytical technique used to determine the elemental composition of materials. XRF analyzers determine the chemistry of a sample by measuring the fluorescent (or secondary) X-ray emitted from a sample when it is excited by a primary X-ray source.
Scanning Electron Microscopy (SEM), also known as SEM analysis or SEM microscopy, is used very effectively in microanalysis and failure analysis of solid inorganic materials. Electron microscopy is performed at high magnifications, generates high-resolution images and precisely measures very small features and objects.
CFS uses one of the above or more bespoke testing to analyze the samples we collet. We use SEM to test for Zinc Whisker, XRF to analyze the majority of other samples to determine there composition. With XRF we can identify almost all the elements of the periodic table and provide extremely accurate feed back on the make up, and therefore source, of contamination.
It is not uncommon for a critical facility to assume that the contamination inside their facility comes from one particular source, only to find, after testing the contamination itself and analyzing its composition, that the contamination stems from another source altogether. Often one that is unexpected. It could be as simple as you looking in the wrong place: contaminants that one might expect to be found in the under the floor, for example, may not be there, but not because the source of contamination is wrong, but rather that the contaminants have already dispersed on the airflow path and are now on the face of the racks. Contamination can continue to ‘appear’ and build up if left unchecked. It can even reappear after a thorough deep clean. Its best to track the source and remediate the problem before undertaking pointless cleaning.
So-called ‘unexplained contamination’ requires a better understanding of the environment, and intelligent analysis of the data presented. By taking samples and testing them, the mysteries can be explained, and the impact of contaminants properly assessed. Technical cleaning of course has its place; but technical cleaning without recognizing and understanding the source of contamination, is effectively throwing good money after bad.