CN2056253U

CN2056253U - Explosion-proof industrial acidometer

Info

Publication number: CN2056253U
Application number: CN 89213823
Authority: CN
Inventors: 王光宁; 缪定; 邵来宝; 顾持平
Original assignee: HANGZHOU TOOL INSTRUMENT AND METER PLANT
Current assignee: HANGZHOU TOOL INSTRUMENT AND METER PLANT
Priority date: 1989-07-07
Filing date: 1989-07-07
Publication date: 1990-04-18

Abstract

The utility model relates to an explosion-proof industrial acidometer. The utility model is composed of a pH sensor and a digital display conversion integrating instrument. The industrial acidometer is primarily designed to aim at the explosion-proof situations. The pH sensor has the design features that an explosion-proof structure and a cavity are adopted. The digital display conversion integrating instrument adopts a series of guard grating circuits for the explosion protection, and the guard grating circuits are used for limiting the voltage and the electric power which pour back toward the measuring field due to the fault. The explosion-proof industrial acidometer can be used for the places with inflammable and explosive mediums, such as the industries of chemical industry, oil refining, medicine, dyestuff chemistry and sugar manufacture.

Description

Explosion-proof industrial acidometer

The utility model belongs to a kind of requirement and uses the industrialization instrument of measuring acidity in explosion-proof occasion.

The industrial PH acidometer that present domestic employing antimony electrode is made is existing to be produced.Be wherein a kind of for example at " the PH acidometer that antimony---mercurous chloride electrode is measured, " of " instrument and meter for automation " o. 11th in 1987 publication.But this class acidometer is non-protected against explosion and is not suitable for measurement inflammable, explosive medium is arranged, as the medium of hydrocarbon, benzene, alcohol, aldehyde, ester, acid, amine, ammonia or the like.These media extensively use in industry such as chemical industry, oil refining, medicine, dying, sugaring.Therefore, non-protected against explosion industrial acidity meter uses in these industry and is restricted.Abroad, though as Japan protected against explosion industrial acidity meter product arranged, structurally with circuit on complicated, price is also expensive.

The purpose of this utility model provides a kind of industrial acidity meter with blast resistance construction, and this industrial acidity meter can use in containing inflammable and explosive medium.

The utility model is made up of two major parts: PH sensor 1 and digital display conversion integrating instrument 2(see accompanying drawing 1).Design philosophy of the present utility model mainly is from explosion-proof angle, and it is a kind of improvement to non-protected against explosion industrial acidity meter.Therefore, the improvement part to explosion-proof needs describes in detail emphatically, and other parts are then done general narration.

PH sensor 1 mainly is made up of antimony electrode 11, solid electrode 12, motor 13, temperature compensation copper resistance 14, flame proof loam cake 15, flame proof lower casing 16, main shaft housing 17, main shaft 18, O-

ring seal

19,20 and other mechanical attachment, (seeing accompanying drawing 2).The design feature of PH sensor 1 is to adopt flame-proof type, and adopt the pattern of a cavity, this cavity is made up of flame proof loam cake 15, flame proof lower casing 16, main shaft housing 17, during the design explosion separation structure, mainly is the temperature rise of considering intensity, explosion-proof slit and the chamber outer surface of cavity.When considering the Intensity Design of flame proof cavity, in order to keep out 10 explosibility tests of 37 ± 0.5% oxygen potpourris, thus on material, select cast steel for use No. 20, and require the dense casting process of employing.The structure of flameproof joint adopts the seam formula as the stationary part flameproof joint.Inlay with brass at cylindrical flameproof joint.Each faying face at cavity all adopts silicone rubber O-

ring

19,20 sealings, and hardness is Shao Er Shi 45～55.In addition, securing member, introducing device, wiring and ground connection have all been done corresponding design,, and after being coated with the ZY-801 anaerobic adhesive on the screw thread, assembled, reached locking purpose as securing member screw bolt and nut structure.The cable of introducing electrical equipment adopts O-ring seal formula introducing device; Cable adopts the anti-flammability cable.The requirement of explosion proof of PH sensor meets the requirement of standard GB 3836.2.

Second portion of the present utility model is a digital display conversion integrating instrument 2, it is formed by measuring safety barrier circuit 21, difference amplification and temperature-compensation circuit 22, temperature compensation safety barrier circuit 23, oscillatory modulation circuit 24, demodulation filtering circuit 25, current limliting safety barrier circuit 26, dc amplification circuit 27, constant current output circuit 28, safety barrier isolator 29, mu balanced

circuit

30,31 and A/D conversion and digital display circuit 32, and its block scheme is seen accompanying drawing 3.Digital display conversion integrating instrument 2 is characterised in that and has adopted oscillatory modulation circuit 24, demodulation filtering circuit 25 and a series of

safety barrier circuit

21,23,26,29.Below circuit is done an explanation.

Measuring safety barrier circuit 21 is current-limiting resistances 41, if it is that late-class circuit is broken down and in the electric current that measuring junction pours in down a chimney is limited in the safety current scope.

Difference is amplified and temperature-compensation circuit 22 mainly is that two comparers 49,50 carry out the difference amplification.45 temperature compensation functions of resistance.

Temperature compensation safety barrier circuit 23 is made up of resistance 44, voltage stabilizing diode 42,43, and its effect is that pouring in down a chimney to the voltage and current of input end of producing under abnormal conditions is limited in the safe voltage and current scope.

Oscillatory modulation circuit 4 is made up of multivibrator 58～66, push-pull amplifier circuit 67～72 and driving circuit 74～78, and its effect is that the direct current signal that differential amplifier circuit 22 is sent here is modulated into high frequency ac signal.

Demodulation filtering circuit 25 is full-wave rectifying circuits, and it is demodulated into DC voltage to modulated alternating voltage.

Current limliting safety barrier circuit 26 is a resistance 86, and it limits the electric current of demodulation filtering circuit 25, and big current feedback is to front stage circuits when preventing fault.

Dc amplification circuit 27 is amplified the direct current signal after the demodulation by amplifier 87 delivers to constant current output circuit 28, and amplifier 94 is delivered to A/D conversion and digital display circuit 32 after again the output of constant current output circuit 28 being amplified.

0～10mA/4～20mA constant current output circuit 28 is that the DC voltage of dc amplification circuit 27 input is amplified through amplifier 102, and triode 99 and resistance 98,100,101 are converted into 0～10mA(II type) or 4～20mA(III type).This continuous current output and the linear transformational relation of sending into of measured signal.

The A/D conversion is that the analog signal conversion that will import becomes digital signal and shows corresponding 0～14PH value indication with digital display circuit 32.

Mu balanced

circuit

30,31 adopts the voltage stabilizer of conventional series connection adjustment type.

Advantage of the present utility model and good effect are to have adopted blast resistance construction, therefore the application of industrial acidity meter are expanded widely.Past some can't use the production line of non-protected against explosion industrial acidity meter, can detect with the utility model, show and feed back to control instrument, help product processing technique precision, robotization, improve the quality of products, alleviate labor strength, also can improve the management of production run.Owing to the utility model compact conformation, price is beneficial to popularization also than import considerably cheaper, and good economic benefits is arranged simultaneously.

Embodiment:

The flame proof cavity of PH sensor 1 is made up of flame proof loam cake 15, flame proof lower casing 16 and main shaft housing 17, (seeing accompanying drawing 2).Cavity adopts No. 20 steel casting to form, the flame proof faying face adopts the seam formula as the stationary part flameproof joint, its structural parameters adopt the maximal clearance of W(flameproof joint)≤0.2mm, the minimum effective length of L(flameproof joint) 〉=25mm, the minimum effective length at L(bolt hole edge to flameproof joint edge) 〉=9mm, on cylindrical flameproof joint, then adopt W≤0.20mm, L 〉=12.5mm, and inlay with brass.In addition, on the smooth finish of flameproof joint and rust preventing, carry out the consideration of appropriateness.Securing member under the situation of no locking device, after being coated with the ZY-801 anaerobic adhesive, is assembled in employing.

The circuit and the component parameter of digital display conversion integrating instrument 2 all indicate on accompanying drawing 4.

Claims

1, a kind of protected against explosion industrial acidity meter is made up of PH sensor 1 and digital display conversion integrating instrument 2, it is characterized in that:

A) PH sensor 1 adopts the pattern of an explosion separation structure and a cavity, and cavity is by flame proof loam cake 15, and flame proof lower casing 16 and main shaft housing 17 are formed; On flameproof joint, inlay with brass; Each faying face of cavity seals with O-ring seal 19,20; On the structure of flame proof faying face, adopt the seam formula as the stationary part flameproof joint.

B) digital display conversion integrating instrument 2 has adopted measurement safety barrier circuit 21, temperature compensation safety barrier circuit 23, oscillatory modulation circuit 24, demodulation filtering circuit 25, current limliting safety barrier circuit 26 and safety barrier isolator 29.

2, industrial acidity meter according to claim 1 is characterized in that: the measurement safety barrier circuit 21 of digital display conversion integrating instrument 1 is a current-limiting resistance 41; Temperature compensation safety barrier circuit 23 is made up of resistance 44, voltage stabilizing diode 42,43; Oscillatory modulation circuit 24 is by multivibrator 58～66, and push-pull amplifier circuit 67～72 and driving circuit 74～78 are formed; Demodulation filtering circuit 25 is full-wave rectifying circuits; Current limliting safety barrier circuit 26 is a resistance 86; Safety barrier isolator 29 is made up of fuse 105,107 and power transformer 106.