FAQ

When we use the pump, in order to maintain its performance and avoid operational problems, there are some maintenance and methods of routine job that need to be understood. The following will introduce how to maintain and inspect the pump to extend the service life of the pump, in order to reduce maintenance costs.

According to the difference in initiative, the types of maintenance are mainly divided into corrective maintenance and preventive maintenance.

What is Corrective Maintenance?

Corrective maintenance: When the pump leaks, the efficiency decreases, stops or the motor failure, resulting in production loss, it is necessary to quickly purchase or install spare parts in an emergency to restore the equipment system to an operational condition.

What is Preventive Maintenance?

Preventive maintenance: Routine or regular (hourly, daily, weekly, monthly, yearly) scheduled inspections aimed at maintaining the equipment in its current state and preventing malfunction, by dismantling devices, replacing seals such as gaskets or mechanical seals, and checking the pump's external and internal parts for wear.

In addition to the necessary to ensure that the pump can operate normally after started through some inspection steps, carrying out the routine preventive maintenance through the following checklists is also a point of pump protection.

Routine inspection:

1. Check the pump body, connection plate and base plate are corroded or damaged.
2. Check whether there is leakage between the pump and the piping.
3. Whether the surface of the motor is damaged or corroded.
4. Whether the pump is operating normally, and check there is any abnormal noise or vibration.
5. Confirm the flow and pressure at the pump inlet.
6. Confirm the flow and pressure at the pump outlet.
7. Confirm the liquid height in the tank.
8. Whether the motor current value is within the rated range.

If there are spare parts, it is also necessary to test run frequently and check whether they can work normally.

Regular inspection:

(depending on the usage conditions and hours, about once every 3 to 6 months)

1. Front casing, rear casing
Check for cracks, abnormal wear, crystallization, or foreign matter attached.

2. Gasket
Check for deformation, corrosion, or swelling.

3. Impeller and inner magnet
Check for scratches or cracks, crack or crystallization on bearings, bearing wear or tear, deformation of the impeller, etc.

4. Shaft
Check for scratches or cracks.

5. Rear casing
Check for corrosion, cracks, holes and scratches.

In addition to the above-mentioned maintenance and detection methods, preventive maintenance also includes the use of monitoring technology to determine the current operating status of system equipment. In order to correct the pump problem before it occurs, the current or power of the pump motor can be monitored by using PTCXPUMP dry run protector. When the current is too high or too low, an immediate warning or automatic shutdown will be issued, which greatly reduces the pump failure probability and maintenance costs.

Considering preventive maintenance, PTCXPUMP sealless magnetic drive pump can reduce the cost of preventive and corrective maintenance because of its simple structure and high durability.

Speaking of flanges, in addition to connecting or closing the pipes, when installing pumps, flange is significant for connected with pipe. After understanding the basic types of flanges and flange faces, the flange standard specification, its resistance pressure capacity, the flange thickness, and applicable countries, also need to be paid attention when selecting.

What are the standards of flanges?
The common flange standards are ANSI, DIN, JIS, GB.
ANSI is most commonly specified in the United States.
DIN is usually specified in Europe.
JIS specifies the standards used for industrial activities in Japan.
GB is the national standard of People's Republic of China.
The international flange standards are mainly use ANSI and DIN, but the flange connection dimensions of these two standards are completely different and unable to exchange.

1. ANSI
Pressure Ratings: 150 LB, 300 LB, 400 LB, 600 LB, 900 LB, 1500 LB, 2500 LB
Flange Types: slip on flange, welding neck flange, threaded flange, lap joint flange, socket weld flange, blind flange
Flange Faces: flat face, raised face, ring type joint, male and female, tongue and groove

2. DIN
Pressure Ratings: PN6, PN10, PN16, PN25, PN40, PN64, PN100, PN160, PN250, PN320, PN400
Flange Types: slip on flange, welding neck flange, threaded flange, lap joint flange, blind flange
Flange Faces: raised face, ring type joint, male and female, tongue and groove

3. JIS
Pressure Ratings: 5K, 10K, 16K, 20K, 30K, 40K, 63K ( 'K' is the unit of pressure rating used in Japan.)
Flange Types: slip on flange, welding neck flange, threaded flange, lap joint flange, socket weld flange, blind flange
Flange Faces: flat face, male and female, tongue and groove

4. GB
Pressure Ratings: 〔series 1〕PN1.0, PN1.6, PN2.0, PN5.0, PN10.0, PN15.0, PN25.0, PN42.0
                              〔series 2〕PN0.25, PN0.6, PN2.5, PN4.0
DIN: PN0.25, PN0.6, PN1.0, PN1.6, PN2.5, PN4.0
Flange Types: slip on flange, welding neck flange, threaded flange, lap joint flange, blind flange
Flange Faces: flat face, raised face, male and female, tongue and groove

ANSI: PN 2.0, PN 5.0, PN 10.0, PN 15.0, PN 25.0, PN 42.0
Flange Types: slip on flange, welding neck flange, threaded flange, lap joint flange, socket weld flange, blind flange
Flange Faces: flat face, raised face, ring type joint, male and female, tongue and groove

The above are the basic flange standards. When considering the flange to be installed with the pump, it is recommended to consult with professionals before selecting.

PTCXPUMP sealless magnetic drive pump provides standard flange specifications(ANSI,JIS,DIN) for easy pipeline connection. It can adjust screw hole position to avoid leakage of inlet and outlet.

Flanges play an important role in connecting pipes, besides knowing the basic types of flanges, it is necessary to further understand the form and application of flange faces. In addition, since the specifications of flanges are very diverse, the standard classification of flanges also needs to be paid attention to when selecting them. The common flange standards will be introduced in the next article.

What are the commonly used flange faces?

1. Flat Face (FF): The smooth surface and simple structure make it easy to process the corrosion-resistant lining. Using full-face gasket to cover the entire flange sealing surface. Due to the large contact area between the sealing surface and the gasket, after pre-tightening, the gasket is easily moved to both sides and be squeezed out of the sealing surface. It is well suited to low pressure and low temperature applications. Flange gaskets are generally divided into metal gaskets and non-metal gaskets, flat face flanges use non-asbestos gaskets.

2. Raised Face (RF): The smooth surface and simple structure make it easy to process. Because of its easy installation, it is the most widely used type of flange employed in the oil and gas and chemical engineering industries. The contact surface of the gasket protrudes from the bolting circle face, concentrating the pressure on a smaller gasket area, thereby increasing the pressure containment capability. Applicable gasket materials include non-metallic flat-ring gaskets and metallic spiral wound gaskets and metal jacketed gaskets.

3. Ring Type Joint (RTJ): The metal ring is placed in the groove, and the gasket will not be pressed into the groove. The compression area is small, and the pressure of the gasket is uniform. When the bolt is tightened, the metal ring is compressed to form a tight seal. Because the gasket and the medium are not in direct contact, it can be used in applications with strict sealing requirements, such as high temperature and high pressure, flammable, explosive and toxic media. Ring type joint flanges use oval ring gaskets or octagonal ring gaskets.


4. Male and Female (MFM): It consists of a male face and a female face, which are used in pairs and are easy to align during installation. Placing the gasket on the female face can prevent the gasket from being extruded, so it can be used in applications with high pressure and strict sealing requirements, but it is not easy to replace the gasket. However, the gasket may still be squeezed out when the male and female flanges are used under high temperature operating conditions. Applicable gasket materials include non-metallic flat gaskets, metallic spiral wound gaskets and metal jacketed gaskets.


5. Tongue and Groove (TG): It consists of a tongue flange and a groove flange, which are used in pairs. The tongue flange is manufactured with a raised ring that is machined into its face, and the groove flange is produced with a matching depression machined onto its face. Placing the gasket in the groove flange, so the compression area is small, the gasket is uniformly stressed, and it is not easy to be extruded. Because the gasket is not in direct contact with the medium, the sealing effect is good, and it can be used in high pressure, flammable, explosive and toxic media, etc. Tongue and Groove flanges use metal and non-metallic flat gaskets, metallic spiral wound gaskets and metal jacketed gaskets.

The above is the basic description of the flange faces. When choosing the flange installed with the pump, it is recommended to consult with professionals before   select it.

When the pump is connected to the pipeline, we generally use flanges, unions or hoses for connection. For the application of medium and large pumps, we often use flanges as the main connection method. Flange refers to the disc-shaped parts used to connect pipes, containers, or fix the shafts. Usually, there are screws and threaded structures to fix them. Flanges are generally used in pairs, the most common in pipeline engineering. The typical connection consist of flanges, gaskets and screws. Gaskets are added to the two flanges and tightly fixed with screws. Widely used in chemical industry, petrochemical industry, firefighting, drainage or water treatment application for liquid transfer solution.

There are countless types of flanges. The commonly used materials are carbon steel, stainless steel, alloy steel, etc. In addition, the thickness, the number of screw holes, and the diameter of the flange need to be selected according to the operation requirements.

The common types of flanges can be divided into Slip On Flange(SO), Weld Neck Flange(WN), Threaded Flange(THDF), Lap Joint Flange(LJ), Socket Weld flange(SW), Blind Flange(BL), and other special types(Specialty Flange), the following basically introduces several main flange types.

Slip On Flange(SO)

A fairly common type with lower installation costs and lower requirements for precise pipe cutting. The steel pipe, pipe fittings are inserted into the inner hole of flange and connected to the pipe through a fillet weld at the flange top and bottom. Since the flange hole is larger than the pipe diameter, it usually requires more welding action than other flanges, so it can effectively prevent leakage. Compared with weld neck flange, it is only suitable for low and medium pressure applications due to the lower neck height.

Weld Neck Flange(WN)

It is a flange that is butt welded to the pipe or fitting, and its installation cost is higher. In contrast to the slip on flange, the distance between the welding joint and the joint surface is large, and the joint surface will not be deformed by the welding temperature. Weld neck flanges are not easily deformed and have high sealing properties, making them suitable for high temperature and high pressure, even for pipelines that transport flammable and toxic fluids.

Threaded Flange(THDF)

The inner hole of the flange is processed into a screw thread and connected with a threaded pipe, which belongs to a non-welded flange. The main feature is easy installation, disassembly and maintenance. However, considering the characteristics of thread structure, it is strongly influenced by the environment, and the temperature in the threaded pipe fluctuates greatly, so it is not suitable for high temperature and high pressure applications.

Lap Joint Flange(LJ)

It consists of two parts, the Stub End and the Backing Flange. The flange is placed on the stub end, and the stub end is butt welded to the pipe joint. The flange can move on the pipe joint. It is mainly used for pipe systems that need to be disassembled frequently for inspection and maintenance. The flanging of the stub end is the sealing surface, and the flange is used to clamp the end of the pipe and the stub end. Because flanging stub end can isolate the flange from medium, it is suitable for conveying corrosive fluids.

Socket Weld flange(SW)

The inner hole of flanges has a socket and is connected by inserting the pipe into the socket and fillet welding around the top. Usually used in smaller, high-pressure pipelines, but not for highly corrosive fluids.

Blind Flange(BL)

It is a flange without a hole in the middle for closing the end of the pipe, with mounting holes around the perimeter and the gasket sealing rings are machined into the mating surface. The function is the same as the head and the cap, and the blind flange is fixed with screws for easy disassembly.

Why do you need to use explosion-proof motors? Explosion-proof motors are mainly used in harsh environments. In the process environment, the air will contain flammable substances, including gas or dust. When a specific concentration is reached, once there is an ignition source, it will cause fire or explosion. Explosion-proof motors can prevent explosions by isolating thermal energy from contact with combustibles and controlling the operating temperature of the motor. When the commonly used sealless magnetic drive pump or centrifugal pump is equipped with an explosion-proof motor, we can call it explosion-proof magnetic pump or explosion-proof centrifugal pump. The explosion-proof motor is selected according to the environment and process. The following will introduce the markings and classifications of explosion-proof equipments.

Explosion-proof marking refers to the mark used to describe the explosion-proof grade, temperature group, protection type and applicable environment of ​​explosion-proof electrical equipment.

The common explosion-proof classification standards mainly include IECEx and ATEX, as well as NEC and CEC.

IECEx: An international, worldwide explosion-proof standard defined by the International Electrotechnical Commission (IEC). An international certification system helps reduce testing and certification costs for manufacturers, allowing the unified standards to be applied in different countries. IECEx is also stricter than ATEX in the certification process.

ATEX: Basically similar to IECEx, but only used in European countries.

NEC: For use in the United States only.

CEC: For use in Canada only.

The following describes the meaning of each indication of the two major standards, IECEx and ATEX.

IECEx ex. 

ATEX ex.

Whether it is temperature, gas or dust, the environment where the equipment is located, etc., there are many factors that determine the specifications of the motor. After the above introduction, when selecting an explosion-proof motor, the meaning of these specifications can be more clearly understood.

Motor is an indispensable part of the industrial automation and one of the most common electrical equipment in life. It is widely used in various electrical appliances, ranging from washing machines and fans in daily life; For industrial applications, pumping, machinery industry and fluid transfer, etc. Motors are also indispensable when pumps are used. Therefore, it is very important to understand and choose a suitable motor. The following describes the differences between normal motors, inverter duty motors and explosion-proof motors.

Normal Motors

There are many types of motors, according to the type of input power, they can be divided into DC motors, AC motors, etc. DC motors can be further subdivided into brushed DC motor, brushless DC motor(BLDC motor); AC motor includes induction motor and synchronous motor. In brief, DC motor controls the rotational speed through voltage, which is easy to control, but not suitable for high temperature and flammable operating environments. The AC motor controls the rotational speed through the frequency of the alternating current, so compared with the DC motor, it is not easy to control the speed, while it can be used in a high temperature and flammable operating environments.

Inverter Duty Motors

A variable frequency drive (VFD) (a.k.a Inverter) is used to change the frequency of the alternating current, by changing and controlling the speed and torque of the AC motor. Therefore, "variable frequency" refers to the way of driving the AC motor. It can be started and adjusted frequently without maintaining full-speed operation and maximum power. When the motor speed is reduced, the output horsepower will also decrease, thereby achieving high efficiency and energy saving. The system control is also more stable than the normal traditional motor.

Explosion-Proof Motors

Mainly used in operating environments where flammable substances exist, such as coal mining, natural gas industry, petrochemical and chemical industries, etc. With the hard explosion-proof shell, it can sustain the explosion pressure inside the motor, and also can isolate the heat from the inflammable materials, so as to avoid the danger of fire or explosion.

According to the explosion-proof form, it can be roughly divided into flameproof motor (symbol d), intrinsic safety motor (symbol i), increased safety motor (symbol e), positive pressure explosion-proof motor (symbol p), non-sparking motor (symbol n), and dust ignition proof motor, etc., depending on the protection level, each has its features and functions.

With a brief understanding of the differences between these motors, I believe it becomes easier to choose the right motor for your needs.


Best Solution For Chemical Transfer – PTCXPUMP Sealless Magnetic Drive Pump

The pump is a general rotating machine, and its operating power comes from the motor. The types of pumps include sealless magnetic drive pumps, mechanical seal pumps or other forms of centrifugal pumps, all of which must be connected to a motor to deliver the fluid.

Motors can be divided into general motors, inverter duty motors and explosion-proof motors. The specifications of the motors are also different according to the application and environment. The following describes about how to select a suitable motor according to the requirements when using a pump.

For different purposes, it can be based on motor specifications, such as the number of poles (Pole), RPM, the frequency (Hz), voltage (V), the install location, IP Rating, and the energy efficiency index to decide which model to choose.

Pole, RPM, Frequency(Hz)

Pole represents the number of magnet poles in the stator magnetic field of the motor. According to the different connection forms of the stator coil windings, different numbers of poles in the stator magnetic field can be generated. The number of poles affects the rotational speed of the motor.

RPM stands for revolutions per minute. For example, the rotational speed of the motor is 3,600RPM, which means that the motor can rotate 3,600 revolutions per minute.

Frequency (Hz) refers to the frequency of the alternating current (AC) is the number of cycles per second in an AC sine wave. Frequency is the rate at which current changes direction per second, in the international measure Hz as the unit, we use 50Hz or 60Hz in the general worldwide.

RPM formula: RPM= Hz x 60(sec/min) x 2 ÷ number of poles

Therefore, under normal circumstances, when the frequency is 60Hz, 2P runs 3600 rpm, 4P runs 1800 rpm, 6P runs 1200 rpm, and so on. It can be seen from the formula that the number of poles, frequency and rotational speed are closely related to each other.

Voltage (V)

The voltage is proportional to RPM, that is, the higher the input voltage, the faster the motor rotates; the lower the input voltage, the slower the motor rotates.

IP Rating& Install Location

IP rating is usually marked with IPXX, such as IP54, IP55, IP56, etc. The first number after it represents the protection against contact and intrusion of solid foreign objects, and the second number represents the protection against ingress of liquid.

The motor can be installed indoors or outdoors according to the IP rating, depending on whether it can resist damage caused by wind, sun, rain, as well as customer operation requirements, noise problems and other conditions.

Energy Efficiency Index

International Efficiency is defined by the International Electrotechnical Commission (IEC), and the energy efficiency levels are divided into IE1, IE2, IE3, and IE4. The larger the number, the better the efficiency and the more power saving.

The above are the relevant specifications that must be referred to when selecting a motor. Next, the differences and applications of general motors, inverter duty motors  and explosion-proof motors will be introduced.

We need to understand the operating condition in the consideration for pump selecting in previously introduced. After understanding the basic concepts, it is necessary to explain how to read the "pump performance curve (H-Q curve)". The performance of each pump model is different, and the most suitable pump must be selected according to the pump performance specifications and the operating conditions provided by the customer.

In the performance curve diagram, the horizontal axis is the CAPACITY (Q), the left side of the vertical axis is the HEAD (H), and the right side of the vertical axis is the EFFICIENCY (%) and shaft power.

The first gray straight dotted line is the shaft power curve under the maximum diameter of the impeller, the second gray straight dotted line is the shaft power curve under the minimum diameter of the impeller, and the red straight line(POWER) is the pump shaft power performance curve that meets the operating requirements provided by the customer.

The first gray dotted curve in the figure is the performance curve under the maximum diameter of the impeller, the second gray dotted curve is the performance curve under the minimum diameter of the impeller, and the red curve(TDH) is the performance curve that meets the customer's operating requirements of the pump, we call duty point, which is what we get by adjusting the size of the impeller, showing the relationship between capacity and head. The green curve(EFF) is the operating efficiency of the pump.

According to the flow demand of the horizontal axis, you can find the duty point by comparing the red curve upwards. By comparing the duty point to the left and right vertical axis, we can know the head and efficiency; then comparing the red line upwards, from the intersection (shaft power) to the right vertical axis, we can know how much the power is under this operating condition.

The efficiency of the pump depends on the duty point, and the change of the duty point will also have a great impact on the field process, so the correct selection of the pump is very important.

If basic preventive maintenance measures are taken, the sealless magnetic drive pump does not often fail. However, in order to have better pump quality and operating efficiency, there are several basic concepts which we need to know. The following describes the main problems that may be encountered when using a pump.

When the flow rate is insufficient or the liquid is not filled with the pump, dry running will occur. If the pump run dry, its internal components (such as impellers, bearings, etc.) will be rubbed, resulting in a lot of frictional mechanical heating and pressure, which will cause the magnet to demagnetize and then damage the pump.

2. Motor Overload

Motor overload occurs when a motor is under excessive load. The primary symptoms that accompany a motor overload are excessive current draw. The main reasons for the excess current are the increased load at the outlet of the pipeline, high lift, poor heat dissipation, blockage of the pipeline, wrong selection of the motor or pump, etc. At this time, the operating power will increase. During a long-time operation insufficient torque and overheating, the motor may cause burn out. 

3.Cavitation 
During the operation of the pump, if the pressure of the pumped liquid drops to the vaporization pressure of the liquid at the current temperature due to the large resistance of the inlet pipeline and the large gas phase of the conveying medium in the local area of ​​ the overcurrent part (commonly found in the impeller), the liquid begins to vaporize to form bubbles. After the bubbles enter the impeller with the liquid, the surrounding high pressure causes the bubbles to shrink sharply and even burst.

At the same time when the bubbles are condensed and broken, the liquid particles fill the cavities at a high speed, which produces a strong water hammer at this moment, and hits the metal surface with a very high impact frequency.
Cavitation is the most harmful to the pump. When cavitation occurs, the pump vibrates violently and makes noise, which will cause damage to the pump bearing, rotor or impeller.

4. Decoupling
As the temperature increases, the strength of the magnetic is weakened or the viscosity of the fluid is too high, the transmittable torque is less than the required torque, and if it continues to operate without cooling or sufficient torque, there will be demagnetization problems, which will cause the magnet to demagnetize and then damage the pump, resulting in failure.

In order to avoid these problems, the dry run protector is used to monitor the current or power of the pump motor when it is running. When the current is too high or too low, an immediate warning or automatic shutdown will be issued, which greatly reduces the probability of pump failure and maintenance costs.


Best Solution For Chemical Transfer – PTCXPUMP Sealless Magnetic Drive Pump

In the selection process of the pumps, the following factors should be considered to select the appropriate pump.

1. First of all, it is necessary to confirm the source of the fluid:

Such as the underground storage tank or the above-ground storage tank, how far the tank is located, the pipeline configuration and other conditions. It is recommended to install the pump as close as possible to the source of the fluid, and the suction pipe should be as short as possible, and also reduce bending or other fittings to reduce the pipe friction loss, which is the resistance of the fluid passing through the pipe.

2. Capacity(Q):

This is an important indicator, which refers to the amount of liquid passing through the pump per unit time, in m³/h, L/min, L/sec. The amount of flow will affect the size of the pump and the thickness of the piping. If the pipe diameter is too small, it will cause extra friction loss and noise problems.

3. Total head(H):

It refers to how high the pump can move the liquid, that is, the vertical height from the source surface of the fluid to the final outlet.

H = Total Head (in meters)= Discharge Head + Suction Head

The height of the head depends on the density of the conveyed liquid, the diameter of the impeller and what type of stage of the impeller.

4. Properties of fluid:

Chemical corrosive, temperature, viscosity, concentration(%), specific gravity and impurities are also the key point of choosing a pump.

◆ Chemical corrosive: According to the difference of the pH value of the fluid and its corrosive, the applicable pump material is also different.

◆ Temperature: When treating water, the temperature has a great influence on the suction capability; other liquids will vaporize at a certain temperature; oil and fats will significantly change their viscosity due to the temperature; The expansion of the material must be taken into account when the heat medium is in a high temperature state; and the chemical fluid will also change its corrosive with the difference of the temperature.

◆ Viscosity, Concentration, Specific Gravity: When the viscosity and concentration of the liquid change, it will affect the corrosive to metals and other materials, and the specific gravity will change accordingly. Therefore, the pump performance will also change.

◆ Impurities: The sand contained in the muddy water and the crystals in the chemical liquid. According to their hardness and content to select the structure of pump, and wear-resistant materials must be used at the same time.



Best Solution For Chemical Transfer – PTCXPUMP Sealless Magnetic Drive Pump

A sealless magnetic drive pump is a conventional centrifugal pumps and sealless magnetic drive pump working principle, the inner magnet and outer magnet are attracted to each other, the outer magnet is connected with motor shaft, and inner magnet is assembly with impeller, as the motor shaft rotates the magnetic attraction forces inner magnet to rotate, thus rotating the impeller and causing chemical liquid to be pumped.
A sealless magnetic drive pump is a conventional centrifugal pump of which design concept is to not use of any mechanical shaft seal. Compared with traditional mechanical shaft seal type of pump, sealless design does not have any leak problem and it is commonly used to transfer hazardous, flammable, explosive, strong acid, strong alkali, or toxic chemical liquid.

Sealless Magnetic Drive Pumps
The sealless design structure is to use rear casing to completely seal the inner magnet, impeller and other wetted parts in the fluid chamber. Outer magnet transmits by motor shaft and inner magnet is connected to the impeller which rotates by magnetic traction and transfer fluid through the pump. Due to the isolation of the fluid by a rear casing, it creates a selless containment. The sealless design brings leak feature.

Mechanical Seal Pump
A mechanical seal pump uses a driven motor to directly rotate the impeller and transfer fluid. The difference of a mechanical seal pump is that a motor shaft goes through rear casing and requires a mechanical seal to prevent any leak. Mechanical seals are consumables and maintenance or replacement is required for long-term use. Fluids often leak through the seal position and cause danger in a mechanical seal pump.

When the pump is running, mechanical heat will be generated due to the rotating parts. A sealless pump uses its own operating fluid to dissipate heat and lubricate the rotating parts. When no fluid enters the pump chamber, the internal temperature will rise and the pump dry runs for a long time, it might cause magnet demagnetization to damage parts.