Laboratories for Metrology
The constant close control on Temperature is a fundamental parameter for Dimensional Metrology according to the International Standard ISO 1 that fixes the reference temperature at 20°C for metrology geometrical specifications (GSS).
The metrological requirements are many and different according to the specific applications, on measurements accuracy of coordinate measuring machines (CMM) and on geometrical parts to be subjected to a precision air conditioning control.
Even if the requirements in Metrology specify that it is not compulsory that all calibrations and tests for the acceptance of mechanical parts must be done at 20°C, it is indicated that a metrological measurement done at a different temperature may lead to apply an offset to adjust deviations on final results.
This effect contributes to the increase of metrological measurements uncertainty.
Calibrations and metrological measurements done with CMM for Dimensional Metrology applications as e.g. large bridge-type machines, bridge-type measuring machines and servo-driven gantry style machine, etc., are performed in precision air conditioning rooms with variable air volumes depending on machines dimension, but always as same requisite is the importance to keep it at a constant control of 20°C and with a reasonably low percentage of relative humidity (<50%) to reduce at minimum level the applying of an offset increasing more reliable and reproducible metrological measurements.
Acceptable limits for temperature gradients are around ± 0,5°C, which has to be set in order to define clearly how much temperature could acceptably move from 20°C during the test activities without penalizing excessively the quality of metrological measurements. For this reason it is important that the precision air conditioning system maintains the temperature under close control and relative humidity (%) higher threshold too through a constant regulation.
S.T.A. Branca Idealair offers three solutions for metrological rooms:
SOLUTION 1 : Precision air conditioning with Branca Climatic unit
High accuracy Metrology measurements are ensured with the precision air conditioning done from Branca climatic units taking particular care at a proper thermal insulation of laboratory room walls and ceiling followed up by Branca Idealair qualified technicians to help guaranteeing the requested thermo-hygrometric parameters below:
View the unit model that fit your Laboratory air volume (m3):
BRANCA PRECISION AIR CONDITIONING: Direct expansion units
TYPE MINI: 9 ÷ 25 m3
TYPE 0: 20 ÷ 50 m3
TYPE 1: 50 ÷ 100 m3
TYPE 2: 100 ÷ 200 m3
TYPE 2S: 200 ÷ 300 m3
TYPE 3: 300 ÷ 500 m3
TYPE 4: 500 ÷ 800 m3
BRANCA PRECISION AIR CONDITIONING: Cooled water units
TYPE MIN: 20 ÷ 100 m3
TYPE MED: 100 ÷ 300 m3
TYPE MAC: 300 ÷ 800 m3
SOLUTION 2: CABINET WITH PRECISION AIR CONDITIONING
Cabinet is equipped with an insulated chamber with a special climatic unit Type 0T that ensures the control of following room parameters listed below:
or for Electrical Metrology applications:
SOLUTION 3 : MEASURE BOX for METROLOGICAL GAUGE BLOCKS PRECISION AIR CONDITIONING
Available range of air volumes can be arranged for Measure box.
It is the ideal solution to get an extremely satisfactory precision air temperature control of small geometrical parts e.g. Johnson gauge blocks inside its small volumes guaranteeing narrowest tolerance limits below:
METROLOGY LABORATORIES REFERENCES:
Prof. Guglielmo M. Tino (Dipartimeto di Fisica e Astronomia and LENS Laboratory)
Università degli Studi di Firenze
Istituto Nazionale di Fisica Nucleare, Sezione di Firenze
POLO scientifico - Via Sansone 1 I-50019 Sesto Fiorentino (Firenze) ITALY
Tel.: +39 055 457-2034 (Office) - 2214 (Lab), - 2462 (Lab)
Fax.: +39 055 457-2121
"... In several occasions I had the opportunity to advice other colleagues about your excellent realization of the precision air conditioning system of our MAGIA laboratory; that was an essential element for the success of the MAGIA experiment whose goal was the accurate measurement of the gravitational constant G which is a fundamental physical constant of metrological interest. ..."
Dott. Vincenzo Greco (CNR Istituto nazionale di ottica)
Largo Enrico Fermi, 6 50125 Firenze (Italy)
Tel.: +39 055 2308271
Fax.: +39 055 2337755
"... As anticipated by phone call we perform temperature measures inside our conditioned room for a period of 3 hours with time sampling of 5 minutes. The data anlyses shows that in 1 hour the flunctuation of temperature values in correspondece to the average value is +/- 0,1 °C (measure uncertainty 2 sigma that represents for a normal distribution corresponds to a level of reliability of 95%) ... "