Pneumatic Latching Air Switch - Threaded - for Spa & Pool Equipment - Universal 21A Max Load
Pneumatic Latching Air Switch - Threaded - for Spa & Pool Equipment - Universal 21A Max Load is temporarily out of stock and will ship as soon as it's available.
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Don't Guess - Ask Us!
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Warranty Information
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Pneumatic Latching Air Switch - Threaded - for Spa & Pool Equip...
Pneumatic Latching Air Switch - Threaded - for Spa & Pool Equipment - Universal 21A Max Load is temporarily out of stock and will ship as soon as it's available.
Tecmark Pneumatic Latching Air Switch - SPDT - Threaded - Universal for Spa & Pool Equipment - 21A Max Load
Genuine Tecmark pneumatic latching air switch, made in the USA, not a cheap low-grade copy. Single Pole Double Throw (SPDT) with Common, Normally Open (NO) and Normally Closed (NC) terminals. Most applications use the Normally Open pair for standard on/off operation, typically the top and middle pins. Commonly used to replace many older Hurlcon, Astralpool, TinyTrol, Pres-Air-Trol, Tecmark, SpaPro, WWDG and similar pneumatic air switches.
- Physically Stocked, unlike most "drop-shipping" websites.
- Shipped from VIC, NSW, WA, QLD
A latching air switch turns equipment on with one press of the air button and off with the next. The button sends a pulse of air down the tube to the switch, so there is no mains voltage at the button.
Commonly fits
- Astralpool and Hurlcon air switch boxes
- Other air switch boxes
- Spa blowers
- Davey, Edgetec, Onga, Balboa pumps
- Other pool, spa, bath and blower equipment fitted with the same style of latching pneumatic air switch
- Other industrial applications.
Specifications
- Action: Latching (alternate action). One press on, next press off.
- Contacts: SPDT. Common, Normally Open and Normally Closed.
- Maximum load: 21A
- Motor rating: 2HP at 250VAC, 1HP at 125VAC
- Mounting: 9/16" (14.3mm) threaded base
- Air connection: Nipple suits 3mm (1/8") ID air tube
- Electrical connections: Standard 6.3mm (1/4") spade terminals
- Operating temperature: -40°C to 82°C
- Cycle life: 100,000+ cycles under full electrical, mechanical and thermal load
- Made in: USA
Before you order
- The first image shows the current style, which replaces many older versions.
- Replaces most latching air switches of the same or lower rating. Do not use it on a load above the ratings listed. Larger motors must be switched through a suitably rated contactor or relay.
- When retrofitting in place of a different style of air switch, the mounting hole needs to be approximately 16mm (5/8") to clear the 9/16" thread. Drill or fill the existing hole to suit.
- Cannot be switched by lung pressure (approx 2-3 PSI). Needs a good quality air button and air line to operate correctly.
- If a switch will not latch, check the air button and tube first. A split button bellows, a perished or loose tube, or water in the tube will stop a good switch from operating.
- Must be installed by a licensed electrician with the power isolated.
Part numbers & cross references
Where the original is a two-terminal switch, connect its two wires to the Common and Normally Open terminals and leave the third terminal unused.
- Tecmark TBS301A, TBS301, TBS-301: SPDT latching, same style.
- Tecmark TBS-305, TBS305A: SPNO (two-terminal) latching, 10A.
- Presair (Pres-Air-Trol) TVA411E: Tinytrol SPST Normally Open latching with a 1/2" thread. The mounting hole needs enlarging to suit.
- Lefoo LF40-01
- HQ34-0002, 34-0002
Also replaces many other latching air switches used in pool, spa, bath and blower applications.
Also searched as: TBS 301, TBS301 A, TBS-301A, TBS 305, TVA 411E, TVA-411E, LF40 01, HQ 34-0002, Tinytrol air switch, Presairtrol air switch, spa air switch, bath pump air switch, blower air switch.
Not sure if it's the right part? Send us a photo of what you're replacing and we'll confirm it before you order.
To the layperson, plumbing sizes and their names can be confusing due to the nominal sizes and naming conventions used.
This is not something we made up. Plumbers and manufacturers have used nominal (meaning ‘by name only’) sizing for decades.
Simply put, in plumbing, named sizes are often not the actual measurements of the pipe, fitting, or part. A PVC pipe called “50mm” or “2"” does not measure 50 mm anywhere. Instead, it follows nominal sizing, an internationally-standardised naming system.
Almost all fittings we use in the pool & spa industry use “pressure PVC” pipe & fittings. Do not confuse with “DWV” or other pipe & fittings and their names and sizes.
Use the Outside Diameter (OD) to check your pipe against fittings. Below is a quick reference for common spa & pool pipe sizes:
| Imperial Name | Metric Name | Pipe Diameter (OD) |
|---|---|---|
| 1/2" | 15mm | ~21.2–21.5 mm |
| 3/4" | 20mm | ~26.6–26.9 mm |
| 1" | 25 mm | ~33.4–33.7 mm |
| 1.5" | 40 mm | ~48.1–48.4 mm |
| 2" | 50 mm | ~60.2–60.8 mm |
| 2.5" | 65 mm | ~75.2–75.5 mm |
To reiterate, these are nominal sizes and are designed to fit matching fittings — not to measure what their name suggests. These are based on PVC Pressure Pipe AS/NZ 1477 Dimensions1.
- º Internal diameters vary slightly by manufacturer and class.
- 1 Not all pool/spa fittings match these dimensions exactly. Some do not follow Australian or international standards. Chinese spas may use proprietary fittings.
Understanding Plumbing Sizes & Nominal Measurements
Plumbing sizes can be confusing. PVC and many other pipe systems use nominal sizes—the size is a name, not the exact measured dimension. This convention is used across most pool and spa systems and other plumbing areas so that pipes and fittings remain compatible.
Why pipe sizes don’t match the measurements
The Nominal Pipe Size (NPS) system standardises pipe dimensions so that pipes, fittings, valves, and accessories interoperate.
Plumbers work with these nominal names every day, but DIYers can be tripped up if they try to match by a tape-measure alone.
How to Measure Pipe Correctly
-
Pipe size is identified by:
- The pipe’s Outside Diameter (OD).
- The fitting’s Inside Diameter (ID) (socket opening).
- Pipe Class / Schedule (e.g., Class 9, 12, 18 or Sch 40) relates to wall thickness and therefore the Internal Diameter (ID) and pressure rating.
- The outside diameter of a fitting is not useful (wall thickness varies by manufacturer).
Hose & Tube Dimensions
Common flexible hose sizes used in pool/spa systems (approximate IDs).
| Imperial Name | Metric Name | Inside Diameter (ID) |
|---|---|---|
| 3/8" | 9–10 mm | ~9 mm |
| 3/4" | 19 mm | ~19 mm |
BSP – British Standard Pipe Thread Sizes
BSP thread names are also nominal. The thread OD will not equal the nominal name.
| BSP Thread Size Naming | Outside Diameter (mm / inch) | TPI |
|---|---|---|
| 1/16" BSP | 7.7 mm / 0.304" | 28 |
| 1/8" BSP | 9.7 mm / 0.383" | 28 |
| 1/4" BSP | 13.16 mm / 0.518" | 19 |
| 3/8" BSP | 16.66 mm / 0.656" | 19 |
| 1/2" BSP / 15 mm | 20.99 mm / 0.825" | 14 |
| 5/8" BSP | 22.99 mm / 0.902" | 14 |
| 3/4" BSP / 20 mm | 26.44 mm / 1.041" | 14 |
| 7/8" BSP | 30.20 mm / 1.189" | 14 |
| 1" BSP / 25 mm | 33.25 mm / 1.309" | 11 |
| 1-1/4" BSP | 41.91 mm / 1.650" | 11 |
| 1-1/2" BSP / 40 mm | 47.80 mm / 1.882" | 11 |
| 2" BSP / 50 mm | 59.61 mm / 2.347" | 11 |
| 2-1/4" BSP | 65.71 mm / 2.587" | 11 |
| 2-1/2" BSP | 75.18 mm / 2.960" | 11 |
| 3" BSP | 87.88 mm / 3.460" | 11 |
| 4" BSP | 113.03 mm / 4.450" | 11 |
| 5" BSP | 138.43 mm / 5.450" | 11 |
| 6" BSP | 163.83 mm / 6.450" | 11 |
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TC-TBS301A
