Overview

The L H-3851/1851 series miniaturized capacitive pressure (differential pressure) transmitter is a new type of transmitter produced by our factory by introducing advanced foreign technology and equipment,
The key raw materials, components, and parts are all imported, and the entire machine has undergone strict assembly and testing. This product has advanced design principles and uniform varieties and specifications
Features such as comprehensiveness, easy installation and use. Due to the complete integration of the two most popular and widely used transmitters in China in terms of appearance, this model (Luo)
The structural advantages of the Smont 3051 and Yokogawa EJA give users a refreshing feeling. At the same time, it is in line with traditional products such as 1151 and CECC
It can be directly replaced when installed, with strong versatility and substitutability. In order to adapt to the continuous improvement and development of domestic automation level, this series of products is designed in addition to
In addition to being compact and exquisite, it also introduces intelligent functions with HART fieldbus protocol.

FEATURES

1. High accuracy;
2. Good stability;
3. Two line system (special can be four line system);
4. Solid components, plug-in printed circuit boards;
5. Small, lightweight, sturdy and earthquake resistant;
6. Range and zero point are continuously adjustable externally;
7. Positive migration can reach 500%; Negative transfer can reach 600%;
8. Adjustable damping;
9. Good one-way overload protection characteristics;
10. No mechanical movable parts, low maintenance workload;
11. Unified structure across the entire series, with strong interchangeability of components;
12. The membrane material in contact with the medium can be selected;
(316L, TAN, HAS-C, MONEL and other corrosion-resistant materials)
13. Explosion proof structure, all-weather use;
14. Intelligent HART fieldbus protocol.

Working principle

The process pressure is transmitted to the center measuring diaphragm of the delta chamber through the isolation diaphragm on both sides or one side, and the filling liquid. The central membrane is a tensioned elastic element
It produces corresponding deformation displacement for the pressure difference acting on it on both sides, and its displacement is proportional to the differential pressure, with a maximum displacement of about 0.1mm
Transform into differential capacitors on the capacitor plates, and convert the differential capacitors into a 4-20mA DC signal output in a two-wire system through electronic circuits. (See above picture)

Function Parameter

★ Target audience: liquids, gases, and vapors
★ Measurement range: 0-0.1kPa to 0-40MPa
★ Output signal: 4-20mA DC (special can be four wire 220V AC)
Power supply, 0-10mA DC output)
★ Power supply: 12-45V DC, usually 24V DC (see figure on the right)

★ Load characteristics: Related to the power supply, the load capacity at a certain power supply voltage is shown in the above figure (load characteristics), and the relationship between load impedance RL and power supply voltage VS is: RL≤50(Vs-12)

★ Indicator: pointer type linear indication with 0-100% equal division scale or LCD liquid crystal or LED digital display.

★ Explosion proof: a. Explosion proof dIIBT4

b. Intrinsically safe iaIICT6

★ Range and zero point: externally continuously adjustable

★ Positive and negative transfer: After the zero point undergoes positive or negative transfer, the absolute values of the upper and lower limits of the measuring range and measurement range cannot exceed 100% of the upper limit of the measurement range. (Intelligent type: Range ratio 15:1)

The maximum positive migration is 500% of the minimum calibration range; The maximum negative transfer is 600% of the minimum calibration range.

★ Temperature range: Amplifier operating temperature range:- 29~+93 ℃ (LT type is:- 25～＋70℃)

Measuring element filled with silicone oil:- 40～＋104℃

When filling high-temperature silicone oil into a flange type transmitter: -20~+315 ℃, ordinary silicone oil:- 40～＋149℃

★ Static pressure: 1. 4, 10, 25, 32MPa

★ Humidity: Relative humidity is 0-100%

★ Volume suction capacity: ＜ 0.16cm3

★ Damping (step response): When filled with silicone oil, it is generally continuously adjustable between 0.2s and 1.67s

technical data

(Without migration, under standard working conditions, filled with silicone oil, 316 stainless steel isolation diaphragm)

★ Accuracy: ± 0.5%, ± 0.25%, ± 0.1% (intelligent type)

★ Dead zone: None (≤ 0.1%)

★ Stability: Absolute value of basic error not exceeding the maximum range within six months

★ Vibration influence: In any axial direction, when the vibration frequency is 200Hz, the error is ± 0.05%/g of the upper limit of the measurement range

★ Power supply impact: less than 0.005%/V of the output range

★ Load impact: If the power supply is stable, the load will not be affected

Other

★ Isolation membrane: 316 stainless steel, Hastelloy C-276, Monel alloy or tantalum

★ Exhaust/Drain Valve: 316 stainless steel, Hastelloy C, Monel alloy

★ Flanges and fittings: 316 stainless steel, Hastelloy C or Monel alloy

★ Contact medium "O" ring: nitrile rubber, fluororubber

★ Filling fluid: silicone oil or inert oil

★ Bolt: 316l stainless steel

★ Electronic casing material: low copper aluminum alloy

★ Pressure connector: flange NPTl/4， Center distance 54mm; Joint NPTl/2 or M20 × 1.5 male threaded ball cone seal, with center distances of 50.8, 54, 57.2mm when equipped with a joint (NPT cone pipe thread complies with GB/T12716-91)

★ Signal line connection hole: Gl/2"

★ Weight: 2.4kg (3851 standard type), 3.5kg (1851 standard type)