When you are designing a system for vacuum conveying, you have a start and an endpoint and often a series of issues in between. To properly design your system, you need to define the following criteria.
Know bulk density
You will need to know this so that you can design the vacuum receiver, which will be larger for lightweight powders. Bulk density also affects the size of the conveying line.
This encompasses vertical and horizontal distance and the number of sweeps or elbow turns, each of which is equivalent to 20 feet of tubing. Avoid back to back elbows and keep vertical runs to a maximum of 12-15 feet.
Is your process batch or continuous?
You will need to define whether your product is delivered through small conveyors into a surge bin (batch) or fed through valves directly into the conveying process (continuous). Once you know the demands of the system, you can calculate the conveying rate. In this way, you know the system is properly sized to meet the demands made of it.
Know your materials
Before you build a system using a vacuum conveyor from an expert such as http://www.aptech.uk.com/pneumatic-conveying-systems/vacuum-conveying/, you must understand your bulk materials. Are they a fine powder, flakes or pellets? Is the material free flowing or abrasive, or even potentially combustible? Knowing whether a material absorbs moisture or is ‘smoky’, such as fine talc, is essential, as is an understanding of the way the material will be introduced into the system so that you can maximise dust control.
Upstream and headroom
An understanding of the upstream process is vital when you design your system, as you need to know exactly where your material is coming from and how these feeders or hoppers influence the conveying process. As for headroom, this may be important when installing a system in an existing plant. Even the smallest conveying system will require around 30 inches, while those with a high throughput rate will require considerably more.
Know your construction materials
Plastics are not suitable for vacuum conveying because of issues around static control and possible contamination; instead, focus on aluminium, carbon or stainless steel. Carbon steel can be coated, but these coatings degrade over time. Stainless steel is a good all-round choice, especially for food and medical grade plastics conveying.