300+ TOP Pneumatic Interview Questions & Answers

1. What Types Of Pneumatic Conveying Systems Are Typically Used?

Essentially, there are two types of pneumatic conveying systems. In dilute phase systems, the solids are suspended in the carrier gas and transported to their destination. In dense phase systems, the solids-to-gas ratio is much higher. The gas in these systems acts more like a piston to push the product to its final destination.

Dilute phase systems are more typical than dense phase systems because they can employ positive pressure displacement or a vaccum system. Dense phase conveying is useful if the product degrades easily (works at lower velocities) or is particularly abrasive.

2. What Is The Most Common Carrier Gas Used In Pneumatic Conveying?

While many applications utilize air as a carrier gas, others are not suited for using air. For example, if the substance being conveyed reactions with moisture in the air or if there is a threat of dust explosions, nitrogen is likely choice.

3. What Are Some Common Problems Associated With Dense Phase Pneumatic Conveying?

Dense phase pneumatic conveying, typically experiences one common problem from system to system: plugging in the line due to a malfunctioning booster valve.

Dense phase systems require these booster systems to introduce new, pressurized air. These boosters are nearly always accompanied by a check valve. If the check valve becomes stuck, the product is allowed to plug the line.

4. What Are Some Common Problems Associated With Dilute Phase Pneumatic Conveying?

Probably the most common problem encountered in dilute phase pneumatic conveying is the wearing of the rotary valve that serves as an air lock where the product is introduced into the system. If excess air is allowed to pass by the rotary valve, this can cause bridging of the material the flow can be slowed or stopped.

5. Why Would You Use Hydraulics Rather Than Pneumatics?

Hydraulics is suitable for higher forces & precise motion than pneumatics. This is because hydraulic systems generally run at significantly higher pressures than pneumatics systems. Movements are more precise (repeatable) because hydraulics uses an incompressible liquid to transfer power whilst pneumatics uses gases.

Pneumatic systems have some advantages too. They are usually significantly cheaper than hydraulic systems, can move faster (gas much less viscous than oil) and do not leak oil if they develop a leak.

6. How Can You Prevent Bridging In A Dilute Phase Pneumatic Conveying System?

Manufacturers of these systems recommend bin agitation or blowing air into the top of the feeding bin. These methods can prevent fine particle from bridging near the rotators valve. Two types of particles that are especially prone to bridging include titanium dioxide and calcined- kaolin clay.

7. What Is A “saltation Velocity” And How Is It Used In Designing Pneumatic Conveying Systems?

In designing, the saltation velocity is used as a basis for choosing the design gas velocity in a pneumatic conveying system. Usually, the saltation gas velocity is multiplied by a factor, which is dependent on the nature of the solids, to arrive at a design gas velocity.

For example:
 the saltation velocity factor for fine particles may be about 2.5 while the factor could be as high as five for course particles such as soybeans could.

8. What Is The Practical Particle Size Limit For Pneumatic Conveying?

As a rule, pneumatic conveying will work for particles up to 2 inches in diameter with a typical density. By “typical density

9. What Is Pneumatic Conveying?

Pneumatic conveying is a method of moving bulk solids from one place to another with the help of a carrier gas. A differential pressure is applied inside a conveying line. The flow always moves from a region of higher to lower pressure.

10. What Are The Differences Between Pneumatics And Hydraulics?

• Working fluid: Pneumatics use air, Hydraulics use Oil
• Power: Pneumatic power less than hydraulic power
• Size: P components are smaller than H components
• Leakage: Leaks in hydraulics cause fluid to be sticking around the components. In pneumatics, air is leaked into the atmosphere.
• Pneumatics obtain power from an air compressor while hydraulics require a pump
• Air is compressible, hydraulic oil is not

11. Where Pneumatic System Is Used?

Any system needs redundancy in work needs pneumatics, because the compressor of the pneumatic system has periodical operations (intermittent work, not as hydraulic pump). The compressed air could be accumulated in tanks with high pressures and used even if the compressor failed.

Pheumatic system is use in an application where the load is light. Because if the load is heavy, pheumatic system should not be use & hydraulic system should be use instead.

12. How Are The Pneumatic System And The Hydraulic System Similar?

Pneumatics use gases such as air or nitrogen, hydraulics use oil or water, both systems use pressure to act on a specific application.

13. What Is A Pneumatic System?

Pneumatic system is a system that uses air to power something. For instance, have you seen the tube systems at bank drive-up tellers? Air is used to push the tubes back and forth from the teller to the customer.

14. Why Would Some Industries Select Pneumatics Over Hydraulic?

Actually, there is need for air reservoir in industrial pneumatics systems. Hydraulics can handle more powerful applications than pneumatics for the same overall dimensions, or can be more compact for the same power.