18" Diameter Round Duct, 48" Long — $79.75
- Diameter: 18"
- Length: 48"
- Gauge: 22 ga
- Material: Galvanized Steel
- Connections: Slip joint
- Fabrication: Made to order in Pittsburgh, PA
- Lead time: Ships in 1 business day
- Returns: Made to order, not returnable
Custom rolled 18" diameter round duct pipe, 48" long, in 22-gauge galvanized steel with a slip joint. Snap-lock longitudinal seam, made to order.
18" Diameter Round Duct, 48" Long: sizing numbers
Worked out from this size's dimensions, so you can check it against your duct design before you order.
| Free area | 1.77 sq ft (254.5 sq in) |
| Circumference | 56.5" |
| Sheet metal in the walls | about 18.8 sq ft |
| Approximate sheet weight | about 27 lb (22-gauge galvanized at 1.406 lb per sq ft, before seams and connectors) |
Airflow by velocity
| Air velocity | Duct (1.77 sq ft) |
|---|---|
| 600 fpm | 1,060 CFM |
| 700 fpm | 1,235 CFM |
| 900 fpm | 1,590 CFM |
| 1,200 fpm | 2,120 CFM |
Airflow is free area times air velocity. Pick the row that matches the velocity your design uses; these figures are capacity at that velocity, not a pressure-loss calculation.
Questions about this size
How many CFM does an 18" round duct carry?
About 1,235 CFM at 700 fpm and 1,590 CFM at 900 fpm. An 18" round duct has 1.77 sq ft of free area, and airflow is free area times air velocity, so multiply 1.77 by the velocity your design calls for.
What is the free area of an 18" round duct?
1.77 sq ft, or 254.5 square inches (pi x diameter squared / 4). Its circumference is 56.5", which is the width of sheet rolled to make it before the seam allowance.
What gauge is an 18" round duct made in?
22-gauge galvanized steel. PMX picks the gauge from the distance around the largest opening: an 18" round duct is 56.5" around, and openings that measure over 54" up to 84" around are built in 22 gauge. The configurator on this page lets you choose 26, 24, 22 or 20 gauge and re-prices it.
How much does an 18" round duct cost?
$79.75 as configured on this page: 22-gauge galvanized steel, made to order. The price comes from the same quoting engine that prices the cart, and changing any dimension in the configurator re-prices it. The same size is $128.50 in aluminum and $177.25 in stainless steel. In galvanized steel, the 12" long version is $55.04, the 24" long version is $63.27, the 36" long version is $71.51, the 60" long version is $96.11.
Can I order a round duct in a different size?
Yes. This page is one published size; the configurator above is loaded with these dimensions and every one of them can be changed to the size you measured, in galvanized steel, aluminum or stainless steel. Each fitting is cut and formed for the order in Pittsburgh, PA.
How fast does an 18" round duct ship, and can it be returned?
It ships in 1 business day from our Pittsburgh, PA shop, by UPS or by LTL freight for large orders, anywhere in the continental US. Shipping is calculated at checkout from the order's weight and destination. Because it is made to the dimensions you order, it is not returnable.
About this size
This page is the 18" Diameter Round Duct, 48" Long configuration of our round duct pipe. It is cut and formed for this order — nothing here is a stock import part. The configurator above is loaded with these exact dimensions, so you can add it to the cart as-is, or change a dimension and it re-prices instantly.