Duluter description

BetaCAP30 is the first born in the BetaCAP family, and akso is the one having got the more substantial evoluttions up to now
His engine is a set of 30 capillaries selected to be nearly equal and grouped in 5 groups to simplify the circuit of gas distribution to send the gas to be diluted and diluting gas to the various capillaries. Different capillaries partitions allow setting 30 different dilution rates step by step”. Differential pressures applied to gases crossing capillaries groups are measured and controlled electronically (PID logic and PWM driving to the relevant valves) : this allows applying calculated set points to proportional valves. The relative simplicity of the diluter functional diagram and of the physics of gas flow through capillaries did allow writing an accurate “diluter transfer function” that automatically controls the BetaCAP30 activity according to simple commands by the user.

Diluter description

This approach allows integrating the diluter with more useful functions : the different viscosities compensation, the certified deviations correction and, last but not least, the continuous coverage of the dilution range : no more just step by step with capillaries. The “continuous dilution mode” also makes wider the dilution range extending it down to 0,5/30 (double width comparing it with 1/30 !) It requires the user sets the target diluted concentration in place of setting the dilution ratio.

Depending on the application type, BetaCAP30 can be supplied in different versions :

• Max diluted gas flow: different values can be supplied alternately by using capillaries with 1, 3 or 4 holes (measures indicated in drawings are in tenths of mm).  The user is free to set different flows in the range 10%….100% of the max. range supplied
• Gas contacted materials: the standard construction is with PVDF (an highly resistant to corrosion fluorinated plastics.     In case of handling toxic or explosive gases, we suggest the “all steel” version with AISI316L stainless steel, where the risk of cracking in tubes or fittings is more  remote.         
• Casing type: depending on the type of moving  (portable or rack mounted) BetaCAP30 can be supplied in a compact and rugged plastic case with handle (ext. Size: 27 x 24,6 x 17,4 cm) or in a 19” rack drawer 3HU with or without an external shocks protection.

The two pressures (gas to be diluted and diluting gas) are controlled electronically by a PID circuit with std. Dev. ± 1mBar over 2.000 to allow applying some special function as Gases viscosities compensation, certified errors correction and continuous diluted gas concentration setting over the entire dilution range The controller variables are the differential pressures input/output on gas to be diluted side and on diluting gas side. A common mode pressures deviation has a very small influence on dilution, but a differential deviation induces important dilution deviations.

Pressures calibration is an important task : it’s made applying an external pressure to all the pressures meter in one time. This assures differential pressures calibration and absolute pressurers calibration.

Differential pressures can have high influence on the dilution but,calibrating zero and span of the three pressures together assures a perfect responces overlapping independently from the applied pressure reference.. This have effects in absolute pressures calibration : hopefully this error have very small consiquences on the dilution accuracy

The dilution module is made by two flat surface shells : capillaries have one half in one and one half in the other shell, with an o-ring in the middle . The other components you can see in the functional diagram are fixed on the external shell surface and the many pneumatic connections are got by crossing holes.  This construction leads to a module very compact and also very rugged : the big shocks due to frequent travels never did cause a capillary breakage, despite they are made by glass , because with glass oxidation is not allowed.

Here it’s shown the “all steel AISI316L option” : just the solenoid valves bodies are made by PEEK.

Technical features