Air Skid Field Guide
For rigging and millwright professionals
Skid Size Calculator
Enter your load and floor type to find the right skid configuration.
Bearing Specifications
| Size | Capacity (lbs) | Op. Pressure (psi) | Inlet | Airflow — Good Floor (SCFM) | Bearing Weight (lbs) |
|---|---|---|---|---|---|
| 12" | 3,000 | 33.3 | 1/8" NPT | 10.8 | 3.5 |
| 17" | 6,250 | 34.7 | 3/8" NPT | 16 | 5.5 |
| 20" | 8,250 | 35.9 | 3/8" NPT | 18 | 6.5 |
| 24" | 12,500 | 35.7 | 3/8" NPT | 22 | 12 |
| 30" | 21,250 | 36.6 | 3/8" NPT | 28.4 | 13.5 |
| 36" | 31,250 | 36.8 | 1/2" NPT | 34.4 | 20.5 |
| 48" | 52,500 | 35.0 | 1/2" NPT | 47.2 | 31.5 |
Compressor Sizing Guide
Always size on airflow (SCFM) — not horsepower. Includes ~25% safety margin.
Quick Selection Rules
| Required Airflow | Recommended Compressor |
|---|---|
| Up to 100 SCFM | 15–25 hp electric rotary screw |
| 100–150 SCFM | 25–30 hp electric rotary screw |
| 150–200 SCFM | 30–50 hp OR 185 CFM diesel |
| 200–300 SCFM | 375 CFM diesel |
| 300+ SCFM | 375–600 CFM diesel |
Supply Hose Sizing Guide
AirFloat Supply Hose Reference (80 psi source)
| Flow | Up to 50 ft hose | 50–150 ft hose |
|---|---|---|
| 50 SCFM | 1/2" ID | 3/4" ID |
| 75 SCFM | 3/4" ID | 3/4" ID |
| 100 SCFM | 3/4" ID | 3/4" ID |
| 150 SCFM | 1" ID | 1" ID |
| 200 SCFM | 1" ID | 1" ID |
| 300 SCFM | 1-1/4" ID | 1-1/4" ID |
Pressure Drop Reference — per 100 ft at 80 psi supply
| Hose ID | 50 SCFM | 75 SCFM | 100 SCFM | 125 SCFM | 150 SCFM | 200 SCFM |
|---|---|---|---|---|---|---|
| 1/2" | 21.6 psi | 50.4 psi | — (exceeds) | — | — | — |
| 3/4" | 2.6 psi | 7.2 psi | 11.6 psi | 17.6 psi | 21.2 psi | — |
| 1" | 0.6 psi | 1.6 psi | 2.8 psi | 3.4 psi | 4.0 psi | 5.4 psi |
| 1-1/4" | 0.4 psi | 0.6 psi | 0.8 psi | 1.0 psi | 1.2 psi | 1.6 psi |
*Green = acceptable (<10 psi drop). Amber = marginal. Red = size up. Values are per 100 ft — scale proportionally for your actual run length.
Floor Requirements
Floor condition is critical to system performance. Review before every job.
Flatness Spec
| Straightedge Length | Max Deviation |
|---|---|
| 6" | 1/16" |
| 3 ft | 1/8" |
| 10 ft | 1/4" |
| 12 ft | 3/8" |
Undulations must be non-abrupt with well-rounded edges. Abrupt irregularities must be repaired.
Levelness Limits
Unleveled floors cause drift — a guide wheel or power drive is required on sloped surfaces.
Floor Condition Checklist
Bridge & Ramp Transitions
Use light gauge sheet metal to bridge seams or ramp to different floor levels. Bridge/ramp must be longer than the bearing diameter so only one edge is transitioned at a time. Add a slight break 2" from leading and trailing edges to keep contact with floor.
Common Questions
An air skid inflates a rubber diaphragm (the air caster) against the floor, creating a thin pressurized air film — like a low-friction air hockey puck. The load floats on this film at roughly 35 psi internal pressure. This allows one or two people to move loads of tens of thousands of pounds with very little push force. Coefficient of friction is typically 0.005–0.01 on a good floor, roughly 10–20× easier than wheeled dollies.
Use the Skid Sizer section to calculate. The basic rule: divide total load weight by number of skids to get load per skid, then add a safety margin. Lifting capacity is rated for “good” concrete — on epoxy floors you can often use a smaller bearing; on poor concrete you may need to step up. All standard sizes (12″ through 48″) are stocked.
Fewer skids is generally better — 4 is the standard starting point and works for most jobs. Use 6 skids when the load is heavier, requires more support points, or needs better load distribution (long or wide equipment, high center of gravity, etc.). For very heavy or oversized loads, larger combinations of skids can be configured — contact the factory for system design help.
Size on SCFM (airflow), not horsepower. Use the Compressor Guide section for exact requirements by model and quantity. For plant use, electric rotary screws are the standard. For outdoor/mobile jobs, towable diesel compressors (185 CFM or 375 CFM) are the go-to. Always size up for long hose runs (>50 ft) or multiple fittings.
The floor is the most critical factor. You need smooth machine-troweled concrete (or better), a non-porous surface, and good flatness (no more than 1/4″ deviation under a 10 ft straightedge). Hairline cracks are fine; wider cracks need to be filled. Expansion joints in the travel path should be avoided or filled with flexible epoxy. For rough or porous floors, steel or Masonite overlays are a cost-effective solution. See the Floor Requirements section for full specs.
Use the Hose Sizing section for a full recommendation. The quick rule: 3/4″ ID handles most systems up to ~130 SCFM on runs up to 150 ft. Step up to 1″ ID for flows above 130 SCFM or any large system. The biggest mistake is undersizing the supply hose — pressure drop kills bearing performance. Also watch your fittings; standard couplers can restrict flow more than the hose itself.
Standard bearings use a high-performance abrasion-resistant urethane diaphragm — durable, flexible, and well-suited for industrial floor surfaces. Stainless steel backplate options are available for washdown environments or applications with corrosives present.
Most items are in stock and ready to ship. If something is out of stock it’s typically available within 4–6 weeks. Rigging kits (complete sets with manifold, pendant, and hoses) are the easiest way to order — everything in one part number. Ships LTL. All that’s needed is a PO with line items and dollar amounts.
Can't find your answer?
For unusual floor conditions, high center-of-gravity loads, custom bearing sizes, or complete system design, contact us.
