Telecommunications Space Environment - Spot Check

What it is

The telecommunications space environment spot check records the dry-bulb temperature and relative humidity of one telecommunications space on the inspection date, read with a calibrated thermo-hygrometer while the equipment is operating. It records the space type and its designated ASHRAE class (Class B for the rooms and enclosures of TIA 569-E, Class A2 for an equipment room under TIA 568.1-E), the site altitude that derates the maximum dry bulb, up to ten measurement points each tagged as an equipment air intake, a cold-aisle point or an enclosure-center point, the computed dew point at each point, the allowable and recommended limits for the class, whether condensation is present, the corrosion coupon rates that set the recommended humidity cap, an optional logged rate of change, and the instrument with its accuracy and calibration due date. Room size, lighting and power belong to the rooms and spaces inspection.

Why it is performed

Telecommunications equipment is rated for an environmental envelope: for a Class B space, 5 to 35 C dry bulb, 8 to 80 percent relative humidity and a dew point of at most 28 C, with every class noncondensing. Readings outside the envelope, or condensation anywhere in the space, stress components, speed corrosion, degrade insulation and shorten equipment life during normal operation. A reading at the air intake, where the equipment actually draws its cooling air, shows directly whether the space is in control on the inspection date; the recorded altitude lets the correct derated maximum be applied for the site; and the operating state ties the reading to the real load the equipment sees in service rather than an idle baseline. The coupon rates add the corrosion picture a thermo-hygrometer cannot see.

When it is performed

Spot checks are taken at acceptance, before the space is returned to full service, to confirm the environment meets the class the space is designated to, and afterward on whatever schedule the owner sets or after an event: a cooling failure and recovery, a growth in equipment load, or a reported condensation or overheating incident. Each record speaks for the readings taken on its inspection date and does not certify continuous control of the space; a rate of change can only come from a trend log. The form is for spaces with powered equipment operating; a space with none cannot conform on it.

How it is typically performed

The inspector records the space type, the designated ASHRAE class, the site altitude, whether tape drives are present and whether condensation is seen, and confirms the equipment is operating. With a calibrated thermo-hygrometer, dry bulb and relative humidity are read at the air intake of at least one powered unit, and at the recommended points: 1.5 m above the floor along the cold-aisle center lines, at least one point per 9 m of total aisle length, or near the center of a distributor enclosure. Each point is tagged with its location type and its rack, aisle or grid position, and the form computes the dew point from dry bulb and humidity by the Magnus formula. The form shows the allowable envelope for the class, derated for altitude, and the recommended range where it applies. Silver and copper coupon rates and their test date set the recommended humidity cap. A logged temperature rate of change may be entered from a trend log. The instrument make, model, serial, stated accuracy and calibration due date are recorded, and the inspector dates the record.

What gets recorded

For each of up to ten points: the location type (equipment intake, cold aisle or enclosure center), the rack, aisle or grid position, dry bulb in C, relative humidity in percent, the computed dew point and the envelope result at that point. For the space: site or campus, building, space identifier and type, the designated ASHRAE class, whether the recommended range is applied, site altitude, equipment operating, condensation, total cold-aisle length, tape drives, a logged rate of change, the equipment maker's environmental specification, the computed allowable dry bulb, humidity and dew point limits and the recommended limits. Coupons: silver and copper corrosion rates, the test date and the computed humidity cap. Instrument: thermo-hygrometer make and model, serial number, stated temperature and humidity accuracy and calibration due date. The inspector, the inspection date, the design documents and revision, comments and deficiencies.

How results are evaluated

The record reads Conforms when every intake reading lies inside the allowable envelope of the class - for Class B, 5 to 35 C dry bulb, 8 to 80 percent relative humidity and a dew point of at most 28 C, the maximum dry bulb derated above 900 m by 1 C per 300 m, limits inclusive - and no condensation is present in the space. An intake reading outside the envelope or condensation reads Does not conform. For the rooms and enclosures of TIA 569-E the designated class can only tighten the Class B envelope, and an equipment room is held to Class A2 under TIA 568.1-E; a blank class still fails readings outside those envelopes, and a looser designated class raises an issue. The record reads Not determined when the equipment was not operating or the question is unanswered, no intake point was taken, a used point is incomplete, or the class, space type, altitude, condensation answer or inspection date is missing. Issues only, never a fail: an aisle or enclosure-center reading outside the envelope, readings outside the recommended range (18 to 27 C and a dew point of minus 9 to 15 C, humidity up to the coupon cap) where it applies, fewer aisle points than the aisle length calls for, a logged rate of change above the table rate, coupons missing, single or older than six months, a calibration due date before the inspection, and an H1 site above 900 m. See TIA 569-E and TIA 568.1-E for the class envelopes and the altitude derating.