What matters needing attention for fluorine plastic pump selection?

There are many kinds of fluorine plastic pumps on the market, so how to choose the satisified fluorine plastic pump? Today we are going to talk about it.

One. Basic basis

1. Flow rate is one of the important performance data of pump selection, which is directly related to the production capacity and transmission capacity of the whole device. For example, design institute process design can calculate the pump normal, minimum, maximum three kinds of flow. When choosing the pump, based on the maximum flow, taking into account the normal flow, in the absence of the maximum flow, usually desirable 1.1 times the normal flow as the maximum flow.

2. The head required by the device system is another important performance data of the pump, which is generally amplified by 5%~10% of the residual head to select.

3. Liquid properties, including the name of the liquid medium, physical properties, chemical properties and other properties. Physical properties include temperature C, density D, viscosity U, solid particle diameter and gas content in the medium, which involves the head of the system, the calculation of effective cavitation allowance and the type of appropriate pump: Chemical properties, mainly refers to the chemical corrosion and toxicity of the liquid medium, is an important basis for the selection of pump materials and the selection of a type of shaft seal.

4. Pipeline layout conditions of the device system refer to the liquid feeding height, liquid feeding distance, liquid feeding direction, the lowest liquid level on the suction side, the highest liquid level on the discharge side, and some data as well as pipe specifications and their length, material, pipe fittings specifications, quantity, etc., In order to carry out the head calculation and the check of NPSH allowance..

5. There are many contents of operating conditions, such as liquid operation T saturated steam force P, suction side pressure Ps (absolute), discharge side vessel pressure Pz, altitude, ambient temperature operation is clearance or continuous, pump position is fixed or movable.

Two. The influence of corrosion

All along, corrosion is one of the most headache hazards of chemical equipment, a slight careless, light damage equipment, heavy accident or even cause disaster. According to relevant statistics, about 60% of the chemical equipment damage is caused by corrosion, Therefore, in the chemical pump selection, we should pay attention to the scientific nature of material selection firstly. There is usually a misunderstanding that stainless steel is "all-purpose material", no matter what medium and environmental conditions are holding out stainless steel, which is very dangerous. The following points for some commonly used chemical media to talk about material selection:

1. As one of the strong corrosive media, sulfuric acid is an important industrial raw material with a wide range of uses. Different concentration and temperature of sulfuric acid on the material corrosion difference is large, for the concentration of more than 80%, the temperature is less than 80℃ of concentrated sulfuric acid, carbon steel and cast iron has good corrosion resistance, but it is not suitable for high-speed flow of sulfuric acid, is not suitable for the material of pump valve; Ordinary stainless steel such as 304(0Cr18Ni9), 316(0Cr18Ni12Mo2Ti) for sulfuric acid medium is also of limited use. Therefore, the pump valve for transporting sulfuric acid is usually made of high silicon cast iron (difficult to cast and process) and high alloy stainless steel (No. 20 alloy). Fluorine plastic has better sulfuric acid resistance, using fluorine lined pump (F46) is a more economical choice. Our company's applicable products are: IHF lined fluorine pump, FSB strong corrosion resistant centrifugal pump, CQB-F PP magnetic pump ( or fluorine plastic magnetic pump) and so on.

2. Hydrochloric acid most of the metal materials are not resistant to hydrochloric acid corrosion (including all kinds of stainless steel materials), high ferrosilicon containing molybdenum can only be used for 50℃, below 30% hydrochloric acid. In contrast to metal materials, the vast majority of nonmetallic materials have good corrosion resistance to hydrochloric acid, so rubber and plastic lined pumps(such as polypropylene, fluoroplastics, etc.) are the best choice for conveying hydrochloric acid. Our company's applicable products are: IHF lined fluorine pump, FSB strong corrosion resistant centrifugal pump, CQB-F PP magnetic pump ( or fluorine plastic magnetic pump) and so on.

3. Nitric acid, most common metals are destroyed by rapid corrosion in nitric acid, stainless steel is the most widely used of nitric acid resistant material, it has good corrosion resistance to all concentrations of nitric acid at normal temperature, it is important to note that the molybdenum stainless steel (e.g., 316, 316 l) of nitric acid corrosion resistance not only no better than ordinary stainless steel (e.g., 304, 321), sometimes even less. For high temperature nitric acid, titanium and titanium alloy materials are usually used. Our company's applicable products are: DFL(W)H chemical pump, DFL(W)PH shielding chemical pump, DFCZ process pump, DFLZP self-priming chemical pump, IH chemical pump, CQB magnetic pump, etc., the material is 304.

4 Acetic acid, it is one of the most corrosive substances in organic acids, ordinary steel in all concentrations and temperature of acetic acid will be seriously corroded, stainless steel is an excellent acetic acid resistant material, 316 stainless steel containing molybdenum can also be applied to high temperature and dilute acetic acid steam. For high temperature high concentration acetic acid or contain other corrosive media, such as harsh requirements, can choose high alloy stainless steel or fluorine plastic pump.?.

5. Alkaline (sodium hydroxide) steel is widely used in the following 80℃, 30% concentration of sodium hydroxide solution, there are many factories in 100℃, 75% is still using ordinary steel, although the corrosion increase, but good economy. The corrosion resistance of ordinary stainless steel to lye has no obvious advantages compared with cast iron, so stainless steel is not recommended as long as a small amount of iron is allowed in the medium. For high temperature lye use titanium and titanium alloy or high alloy stainless steel. Our company's general cast iron pump can be used for low concentration of lye at room temperature, when special requirements can use all kinds of stainless steel pump or fluorine plastic pump.

6. Ammonia (ammonia hydroxide), the corrosion of most metals and nonmetals in liquid ammonia and ammonia water (ammonia hydroxide) is slight, and only copper and copper alloys are unsuitable for use. Most of our products are suitable for conveying ammonia and ammonia water.

7. Salt water (sea water) o, ordinary steel in sodium chloride solution and seawater, salt water corrosion rate is not too high, generally must use paint protection; All kinds of stainless steel also have a very low uniform corrosion rate, but may cause local corrosion due to chloride ions, usually 316 stainless steel is better. Our company has SS316 material configuration for all kinds of chemical pump.

8. Alcohol, ketone, ester, ether, common alcohol media are methanol, ethanol, ethylene glycol, propanol, ketone media are acetone, butyl ketone, ester media have a variety of methyl ester, ethyl ester, ether media have methyl ether, diethyl ether, butyl ether, etc., they are basically not corrosive, commonly used materials can be applied. The specific selection should also be based on the properties of the medium and the relevant requirements to make a reasonable choice. It is also worth noting that ketones, esters, ethers have solubility for a variety of rubber, and avoid mistakes when choosing sealing materials.

Three. Influence of other factors

In general industrial pump, the leakage amount in the pipeline system can be ignored in the process flow, but the influence on the flow rate must be considered when the process changes. If the agricultural pump is the use of open channel water, Seepage and evaporation must also be considered.

Pressure: suction tank pressure, drain tank pressure, pressure difference in piping system (head loss).

Piping system data (pipe diameter, length, type and number of pipe fittings, geometric elevation from suction tank to pressure tank, etc.).

A device characteristic curve should be drawn if necessary.

Four. Influence of pipeline

In the design and layout of the pipeline, the following matters should be noted:

A. Reasonable selection of pipeline diameter, pipeline diameter is large, under the same flow rate, liquid flow speed is small, small resistance loss, but the price is high, pipeline diameter is small, will lead to a sharp increase in resistance loss, so that the selected pump head increase, the distribution of power increase, cost and operating costs are increased. Therefore, it should be considered from the technical and economic perspectives.

B. The maximum pressure that the discharge pipe and its pipe joint can bear shall be considered.

C. Pipe layout should be arranged into straight pipe as far as possible, minimize the accessories in the pipe and reduce the length of the pipe as far as possible. When it is necessary to turn, the bending radius of the elbow should be 3 ~ 5 times of the diameter of the pipe, and the Angle should be greater than 90℃ as far as possible.

D. The discharge side of the pump must be equipped with valves (ball valves or globe valves, etc.) and check valves. The valve is used to adjust the working point of the pump. The check valve can prevent the pump from reversing when the liquid flows back and prevent the pump from being hit by the water hammer. (When the liquid flows backwards, it will produce huge reverse pressure, which will damage the pump)

Five. Influence of flow head

Flow determination

A. If the minimum, normal and maximum flow rates have been given in the production process, the maximum flow rate shall be considered.

B. If only normal flow is given in the production process, a certain allowance shall be considered.

For NS100 large flow low head pump, the flow margin is 5%; for NS50 small flow high head pump, the flow margin is 10%; for 50≤ NS ≤100 pump, the flow margin is 5%; for pumps of poor quality and poor operating conditions, the flow margin should be 10%.

C. If the basic data is for weight flow only, it shall be converted to volume flow.

Six. The effect of temperature

The transmission of high temperature medium puts forward higher requirements for the structure, materials and auxiliary system of the pump. The following talk about the cooling requirements of different temperature changes and the pump type applicable to the company:

1. For the temperature below 120℃ medium, usually do not set up a special cooling system, the use of its own medium for lubrication and cooling. Such as DFL(W)H chemical pump, DFL(W)PH shielded chemical pump (more than 90℃ shielded motor protection level should be H class); However, DFCZ common type and IH chemical pump can make the upper limit of temperature reach 140℃~160℃ because of the suspension structure. The highest operating temperature of IHF lined fluorine pump can reach 200℃; Only CQB ordinary magnetic pump temperature does not exceed 100℃. It is worth mentioning that the medium that is easy to crystallize or contains particles should be equipped with sealing surface flushing pipeline (the design has interfaces).

2. For more than 120℃, 300℃ within the medium, generally in the pump cover must be equipped with a cooling chamber, the sealing chamber should also be connected to the coolant (should with a double end face mechanical seal), when the coolant is not allowed to penetrate into the medium, should take its own medium after cooling access (it can be achieved through a simple heat exchanger). At present, our company has DFCZ chemical process pump, GRG high temperature pipeline pump and HPK hot water circulation pump (under development) for selection, in addition, CQB-G high temperature magnetic pump can be used for high temperature medium within 280℃.

3. For the high temperature medium above 300℃, not only the pump shell part needs cooling, the suspension bearing chamber should also be equipped with a cooling system, the pump structure is generally the central support form, the mechanical seal is best to use the metal bellows type, but the price is high (the price is more than 10 times of the ordinary mechanical seal). At present, our company only has DFAY modle centrifugal pump operating temperature can reach 420℃(under development).??

Seven. The influence of sealing

No leakage is the eternal pursuit of chemical equipment, it is this requirement to promote the magnetic pump and shield pump applications are expanding day by day. However, there is still a long way to go to truly achieve no leakage, such as the service life of magnetic pump isolation sleeve and shielding pump shielding sleeve, the problem of material pitting corrosion, the reliability of static seal and so on. Some basic information about sealing is introduced briefly as below:?

1. Sealing form for static seal, usually only two forms of gasket and sealing ring, and the sealing ring and O ring is the most widely used; For dynamic seal, chemical pump rarely uses packing seal, mainly mechanical seal, Mechanical seal has a single end face and double end face, balanced type and non-balanced type, Balancing type is suitable for the sealing of high pressure medium (usually refers to the pressure is greater than 1.0Mpa), double end face mechanical?seal is mainly used for high temperature, easy crystallization, viscosity, containing particles and toxic volatile medium, double end face mechanical seal should be injected into the sealing cavity isolation fluid, the pressure is generally higher than the medium pressure 0.07~ 0.1Mpa.??

2. Sealing material, chemical pump static sealing material generally uses fluorine rubber, special circumstances only use PTFE material; The material configuration of the mechanical seal dynamic ring and static ring is the key, it Is not hard alloy on hard alloy is the best, the high price is on the one hand, it is not reasonable as there is no hardness difference, so it is best to treat according to the characteristics of the medium.??

For more technicial questions please feel free to contact Kelly~

Kelly - International Trade Pumps Engineer

Anhui Tenglong Pump And Valve Manufacturing Co., Ltd.(TEFLOW)

No. 30 fortune east road, Jingkai district Jing County, Xuancheng City, Anhui Province, China

Web:www.teflowpump.com,????????????????????????????????????????????????????tlgroup.en.alibaba.com,???????????????????????????????????????????????????teflow-pumps.en.made-in-china.com?

Tel:+86-15156345852

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