Key Differences Between Gear Pumps
Explore the structural, efficiency, and noise differences.
| Features | External Gear Pumps | Internal Gear Pumps |
|---|---|---|
| Design | Two same gears side by side. | One gear inside another gear. |
| Pressure Handling | Can handle higher pressure. | Handles medium pressure. |
| Temperature Tolerance | Good for medium or low heat fluids. | Can move hot fluids, often with a heater. |
| Flow Characteristics | Bigger outlets and high flow. | Smaller outlets and high flow. |
| Bi-directional Flow | Can go both ways if spur gears are used. | Always goes both ways. |
| Noise Level | Usually makes more noise. | Much quieter operation. |
| Efficiency with Thick Fluids | Less efficient with thick fluids. | More efficient with thick fluids. |
| Self-Priming Capability | Limited self-priming capabilities. | Excellent self-priming capabilities. |
| Cost | Less expensive initially. | More expensive initially. |
| Application Suitability | Best for high pressure and thin fluids. | Best for thick or sticky fluids. |
You need to pick between external gear pumps and internal gear pumps. These pumps work in different ways. External gear pumps have two gears that fit together. They move fluid around the outside of the gears. Internal gear pumps have one gear inside another gear. They move fluid between the teeth of the gears. These differences change how much noise the pumps make. They also change how well each pump works with different fluids. The differences affect how efficient each pump is. When you compare gear pumps, your choice will change your results.
Key Takeaways
- Learn how gear pumps are built. External gear pumps have two gears outside that fit together. Internal gear pumps have one gear inside another gear. This changes how well they work and how much noise they make.
- Pick the right pump for your fluid. Internal gear pumps are best for thick or sticky fluids. External gear pumps work well with thin liquids and high pressure.
- Think about noise when you choose a pump. Internal gear pumps are quieter than external gear pumps. They are good for places where less noise is needed.
- Look at how well each pump works. Internal gear pumps work better with thick fluids. External gear pumps are best for thin fluids and high pressure.
- Choose a pump that fits your needs. Things like flow rate, working pressure, and what you use it for matter for best results.
Structure of Gear Pumps
If you know how gear pumps are built, you can pick the right one. Both external gear pumps and internal gear pumps use gears to move fluid. But their shapes and parts are not the same. These changes affect how each pump deals with pressure and flow. They also decide what fluids you can use.
External Gear Pumps
External gear pumps have two gears that look the same. The gears spin in different ways. They sit next to each other inside the pump. When the gears turn, they catch fluid between the teeth and the case. This moves the fluid from where it comes in to where it goes out. The small space between the gears and the case helps the pump handle more pressure. This type is good for fluids like lube oil, fuel oil, asphalt, and bitumen.
Tip: You will see external gear pumps in cars, oil and gas, and chemical plants.
Here is a simple table to compare gear types:
| Type of Pump | Gear Configuration | Characteristics |
|---|---|---|
| External Gear Pump | Has two gears that spin in opposite ways. | Usually makes more noise and is less efficient than internal gear pumps. |
| Internal Gear Pump | Has a big outer gear and a small inner gear inside. | Often works more quietly, is smoother, and uses fluid better. |
External gear pumps have small gaps and many bearings. This makes them not good for fluids with rough bits. Over time, the gaps can get bigger. This makes the pump work less well and lets more fluid slip by. Even a small change in the gap can hurt how the pump works.
Internal Gear Pump
Internal gear pumps are built in a different way. They have a big outer gear and a small inner gear inside. The small gear is not in the center of the big gear. Fluid moves between the teeth as the gears spin. This makes the flow smooth, even with thick or sticky fluids.
Internal gear pumps work best at slow speeds. You can use them for liquids that need gentle care, like food, paint, and soap. They are also good for oils and glue. Some have a heating jacket to help with hot fluids.
Note: Internal gear pumps are great when you need to move fluids gently.
Operation Differences
You can see some big differences in how these pumps work:
| Feature | External Gear Pump | Internal Gear Pump |
|---|---|---|
| Design | Two same gears side by side, spinning together. | One gear inside another gear. |
| Pressure Handling | Can handle higher pressure. | Handles medium pressure. |
| Temperature Tolerance | Good for medium or low heat fluids. | Can move hot fluids, often with a heater. |
| Flow Characteristics | Bigger outlets and high flow. | Smaller outlets and high flow. |
| Bi-directional Flow | Can go both ways if spur gears are used. | Always goes both ways. |
- External gear pumps can reach up to 500 bar pressure. This makes them good for jobs that need lots of pressure.
- Internal gear pumps do not have a part to stop too much pressure. You must set and watch the system pressure.
When you pick a pump, think about the fluid you want to move. Internal gear pumps are best for oils, glue, and thick fluids. External gear pumps are better for lube oil, fuel oil, asphalt, bitumen, and molasses.
Quick List:
- External gear pumps: Best for high pressure and fluids without rough bits.
- Internal gear pumps: Best for gentle, thick, or sticky fluids.
Gear pumps have gotten better over time. Some internal gear pumps now use a crescent block to handle more pressure. Engineers also use new models to study how pumps work and sound. This helps make pumps quieter and better.
If you know these differences, you can pick the best gear pump for your job.
Efficiency Comparison
Fluid Handling
When you pick a gear pump, think about the fluid. Internal gear pumps work well with thick and sticky liquids. You can use them for things like chocolate, glue, or heavy oils. These pumps give smooth flow and work well, even with hard fluids. External gear pumps are better for thin liquids like fuel oil or hydraulic fluid. They move these fluids fast and keep the flow steady.
Here is a table to help you see how each pump type works with different fluids:
| Pump Type | Efficiency with High-Viscosity Fluids | Self-Priming Capabilities | Precision Metering | Robustness and Versatility |
|---|---|---|---|---|
| Internal Gear Pumps | More efficient | Excellent | High | Moderate |
| External Gear Pumps | Less efficient | Limited | Moderate | High |
Tip: If you need to move thick or sticky fluids, internal gear pumps work better. For thin fluids and jobs that need strong, steady flow, external gear pumps are a good pick.
Viscosity and Pressure
Viscosity and pressure are important for pump performance. Internal gear pumps handle thick fluids easily. They can pull fluid in by themselves. You do not have to worry about air or gas in the line. These pumps start up fast and keep working, even with thick fluids.
External gear pumps can handle higher pressure. You can use them for jobs that need strong force, like hydraulic systems. They work best with thin fluids and can reach up to 500 bar. Internal gear pumps work at lower pressure but are great for thick fluids.
Here is a table that shows how each pump type compares in pressure and best use cases:
| Pump Type | Pressure Capability | Best Use Cases |
|---|---|---|
| External Gear Pump | High pressure | Hydraulic fluid applications, thinner fluids |
| Internal Gear Pump | Low pressure | High viscosity fluids like asphalt, chocolate, and adhesive |
Note: If your job needs high pressure, pick an external gear pump. If you need to move thick fluids, internal gear pumps are the better choice.
Energy Use
Both gear pumps work well when used for the right job. Internal gear pumps use less energy with thick fluids. They do not waste power because they move heavy liquids smoothly. External gear pumps use energy well with thin fluids and high-pressure jobs.
You can see the efficiency ratings for both pump types in the table below:
| Pump Type | Volumetric Efficiency | Mechanical Efficiency |
|---|---|---|
| External Gear Pump | Up to 93% | Similar to internal gear pumps |
| Internal Gear Pump | Up to 93% | Similar to external gear pumps |
Both pumps give you similar efficiency if you use them with the right fluid and pressure. Internal gear pumps also pull fluid in by themselves. You do not need to prime them by hand, which saves time and energy.
| Feature | Internal Gear Pumps | External Gear Pumps |
|---|---|---|
| Suction Capabilities | High self-priming capabilities, can evacuate air or gas easily | N/A |
| Priming Efficiency | Eliminates need for manual priming, reduces downtime | N/A |
Tip: Always match the pump type to your fluid and pressure needs. This helps you get the best pump performance and saves energy.
If you want your gear pumps to work their best, pick the right type for your job. NTGD has both internal and external gear pumps for your needs. You can ask NTGD for help choosing the best pump for your job.
Noise Levels in Gear Pumps
External Gear Pump Noise
External gear pumps are usually louder when they run. This is because their gears fit together on the outside. This makes the pump shake more and sound louder. The number of teeth on the gears changes how much the pump shakes. If a gear has 6 teeth, the shaking is about 25%. If you add more teeth, the shaking goes down. But it is still more than with internal gear pumps.
| Number of Teeth (z) | Internal Gear Pump Pulsation Rate (%) | External Gear Pump Pulsation Rate (%) |
|---|---|---|
| 6 | 12.5 | 25.0 |
| 8 | 9.8 | 18.5 |
| 10 | 7.5 | 14.2 |
| 12 | 5.9 | 11.8 |
External gear pumps also make noise from moving fluid and shaking parts. The sound can travel through the air. If you make the outlet pressure higher, the noise can go up by 3.5 dB. Changing the pump’s design, like how pressure moves inside, can make it quieter by up to 11%.
Internal Gear Pump Noise
Internal gear pumps are much quieter. Their shape helps balance the forces inside. This means less shaking and less noise. The shaking is always lower, no matter how many teeth the gear has. For example, with 12 teeth, the shaking is only 5.9%. This makes the pump run smoother and keeps the noise down.
Internal gear pumps make less noise in the fluid, in the pump, and in the air. They also use energy better, which is good for the environment.
Reducing Noise
You can make both types of pumps quieter by using smart designs:
- Pick helical gears or special teeth to lower shaking and noise.
- Use parts that soak up vibration and better gear shapes to cut noise.
- Choose pumps with gears that fit together well for less sound.
- Try NTGD gear pumps if you need a quiet pump.
Tip: Always pick the right pump for your job. If you want less noise, look for pumps made to be quiet.
NTGD can help you find a pump that keeps your work area quiet and works well. Ask NTGD for help picking the best gear pump for your needs.
Application Suitability
When to Use External Gear Pumps
Pick external gear pumps for jobs that need high pressure. They work best with thin or medium liquids. These pumps give steady flow and are very reliable. Many industries use them because they can handle lots of fluids. They also run fast. You will find them in cars, factories, and oil and gas work.
Here is a table showing where external gear pumps are used:
| Industry | Applications |
|---|---|
| Automotive | Engine lubrication, fuel transfer, power steering, hydraulic systems |
| Industrial Manufacturing | Hydraulic systems, lubrication, cooling systems, metering and dosing |
| Oil and Gas | Oil transfer, lubrication and cooling, metering and dosing, hydraulic systems |
External gear pumps are great when you need strong pressure. They also work well when you want a powerful pump. These pumps cost less to buy at first. This makes them a smart choice for many jobs.
When to Use Internal Gear Pump
Use internal gear pumps for thick or rough fluids. They are good for moving things like chocolate, glue, or heavy oils. Their design helps them suck up thick liquids easily. They give smooth flow, even with sticky stuff. Internal gear pumps are gentle with fluids and can start by themselves.
You will see internal gear pumps in food factories and chemical plants. They are used when you need to move thick or special fluids. They can handle many types of thick liquids. They also last longer with rough fluids.
Note: Internal gear pumps cost more at first, but they work better with thick or rough fluids.
Selection Factors
When you pick between these pumps, think about a few things:
- Flow rate: Make sure the pump gives enough flow.
- Working pressure: Pick a pump that can handle your top pressure.
- Speed: Match the pump speed to your system.
- Materials and durability: Choose strong pumps that last long.
- Sealing and leakage control: Good seals stop leaks and keep things safe.
- Maintenance: Take care of your pump to keep it working well.
Here is a table to help you compare:
| Selection Criteria | Internal Gear Pumps | External Gear Pumps |
|---|---|---|
| Suction Capabilities | Better for high viscosity fluids | Less effective for high viscosity fluids |
| Cost | More expensive | Less expensive |
| Speed | Operate well at lower speeds | Operate well at high speeds |
| Application Suitability | Best for high viscosity fluids | Suitable for a wider range of applications |
NTGD has both kinds of gear pumps. They can help you pick the right one for your job. You can trust NTGD to match the pump to your fluid, pressure, and flow needs. This helps your pump work well and last a long time.
You have seen how gear pumps differ in structure, efficiency, and noise. Internal gear pumps use gears that mesh inside each other and work well with thick fluids. External gear pumps have gears that mesh outside and handle many types of fluids. Here is a quick table to help you compare:
| Feature | Internal Gear Pumps | External Gear Pumps |
|---|---|---|
| Gear Configuration | Internal mesh | External mesh |
| Noise Level | Lower | Higher |
| Viscosity Handling | Best for thick fluids | Good for many fluids |
When you choose gear pumps, think about your fluid, pressure, and accuracy needs. Always match the pump type to your job. This helps your system run better and last longer. For help finding the right gear pumps, reach out to NTGD.
