SMC Vs. Airlift Valves

In this thread I will compare the top 2 fastest flowing valves form my previous test.

These 2 valves are the

Airlift ½” valve
SMC ½” VXD line Valve

I will now explain the different valve designs and their benefits.

First you will see the size difference.

And the different is finishes. The Airlift valve has a nickel plated finish that will hold its luster in the elements. Brass tends to tarnish and form a dark golden color.

You will also note the pilot sections orientation.
On the SMC the pilot is off to the side of the valve the Airlift valve is on top.
The difference can play a factor in your mounting. And should be taken into consideration when choosing what valve is best for your location.

The SMC valve’s bracket makes the entire valve assembly protrude from the mounting surface much farther then the Airlift valve,

Below are to pictures with mounting brackets attached. (From SD’s Site)

Below is a side on shot of the 2 valves. Note the Airlift’s valve ports have a much thicker section of material at the port This allows a stronger mount if the valve is attached directly to the tank with no bracket.

Now We will look inside,
On the Left is the SMC valve and on the right is the Airlift valve.
Note both have almost the exact same size and design.
But as we look closer below I will point out a few key differences.

First we will look inside the Airlift valve,
The center seal section is a well machined surface that promotes a clean tight seal every time. One thing to note here is the Airlift valve center port or Orifice is smaller then the SMC valve this slight difference (only about 1/32”) is the reason it was a fractional slower then the SMC valve.

This is the inside of the SMC valve
Note the air passage around the orifice is a steep angle The aggravates the air passage more then the Airlift’s Smooth curve inside. ( this starts to come into play at high pressures.

Here you can compare,

Next crucial point of any valve is the Diaphragm this is what does the main work of the valve and is crucial to its operation.

Note the stark difference between the SMC (right) and Airlift (Left)

The diaphragm of the Airlift is almost 3X thicker then the SMC This extra material allows for small abrasions (like rust partials) that get into the valve from puncturing the membrane

Also the Airlift valve has a much thicker section of material at the seal point and a large brass plug to help hold pressure (also plays a large role in high pressure applications)
Last I would like to point out the air passage point in the Airlift valve has a Brass insert to keep the rubber from ripping apart if ice or foreign material enters this passage also keeps the diaphragm from ripping or tearing under high flow rates.

Above you can see that the Airlift (Top) allows the diaphragm to travel further up into the head allowing greater air to pass over the orifice. By almost 1/16” more travel

Next point I would like to make is many of you in colder climates will understand this,
When your valve freezes in the winter 9/10 times it is caused my water vapor freezing into ice in the pilot section of the valve

Below is the Airlift valve,

You can see that all ports are direct no bends or angles this allows least chance of partials freezing and locking a passage.

The SMC valve has a maze of passages,

Note this is the primary inlet for the pilot.

The one thing the SMC valve has going for it is its pilot section it is well built and robust.
It is a little bit larger then the Airlift valve but the larger size is not as efficient at high pressures.

And here is the Airlift valve fully disassembled.

I hope this helps you in deciding a Valve for you next purchase.

Now Last point to compare is Price,
As of 4/21/06 the Process are as follows from SD,
Airlift ½” $49.99
SMC ½” $48.99

A difference of $1

Don’t get me wrong the SMC is a great valve as well. But I feel in concussion the Airlift valve will work better under high pressure and will last longer with fewer problems.

IF you have any questions or would like be to compare anything you did not see please let me know I would be happy to post up more.