Specification sheet
Model NDC
Absolute pressure
transmitter
Deltapi N Series
Pneumatic Transmitters
GENERAL CHARACTERISTICS
The blind type absolute pressure transmitter, mod. NDC, is
used to measure an absolute pressure and convert it into a
proportional pneumatic signal.
The instrument works on the force-balance principle and
consists of two main units:
the measuring unit comprises a main body which houses a
bellows unit, clamped in the main body forging by means of a
flange. The bellows unit incorporates an evacuated reference
chamber and releves the absolute pressure applied to the
positive connection port. The bellows unit can withstand the
maximum overrange without damage.
the transmission unit converts the differential force applied to
the measuring element into a proportional output pneumatic
signal.
The output pressure, generated by a flapper nozzle relay, is fed
to a feedback bellows with a rising pressure until the bellows
force balances that of the measuring element.
Span value continuously adjustable by an internal micrometric
screw.
Zero value adjustable by an external screw.
Mounting in a vertical position on 2in diameter pipe by a
special bracket.
OPTIONAL EXTRA FEATURES
A zero suppression device allows to set as a zero of the
transmitter a measured variable value different from the
absolute zero.
The sum of the zero suppression value (S) plus the calibrated
span cannot exceed the upper range limit (M) suitable by the
bellows capsule : S + span ≤ M (see table).
Air filter regulator can be directly mounted on the transmitter,
with or without pressure gauge, and connected with piping and
fittings either in stainless steel or copper.
Special versions of air filter regulator and gauges, in stainless
steel, are available on request.
Oxygen measurements a special degreasing and final test
operations can be required on the oxygen measuring
transmitter.