{"product_id":"castair-thb-bowl-float-drain-afd3","title":"Castair THB Bowl Float Drain AFD3","description":"\u003cp\u003eThe \u003cstrong\u003eCast Air AFD3\u003c\/strong\u003e is a float-operated automatic drain valve designed specifically for Castair THB-series filter bowls, priced at $47.74. It connects via a 1\/4\" NPT fitting and provides passive, fully automatic condensate drainage from THB bowl assemblies without any electrical connection, timer, or manual intervention. If your THB filters are accumulating water that is making it downstream into your air lines and tools, the AFD3 is the direct-fit solution.\u003c\/p\u003e\n\n\u003cp\u003eThe THB-series filter bowls are a common configuration in Castair compressed air systems. Like all inline compressed air filters, THB bowls collect condensate as part of their job — separating moisture from the air stream before it reaches downstream equipment. The problem comes when that condensate is not removed regularly. An overfull filter bowl passes moisture downstream, effectively making the filter useless. The AFD3 keeps the bowl evacuated continuously, so the filter keeps working the way it is supposed to.\u003c\/p\u003e\n\n\u003ch2\u003eHow the Float Drain Works\u003c\/h2\u003e\n\u003cp\u003eThe AFD3 uses a mechanical float mechanism — the same principle used in carburetor float bowls and fluid level controls. As condensate collects at the bottom of the THB filter bowl, the float inside the AFD3 rises with the water level. When the water reaches the drain threshold, the float opens the drain port and evacuates the condensate. When the bowl is clear, the float drops and the drain port closes. The cycle is passive and continuous — no programming, no power, no maintenance schedule.\u003c\/p\u003e\n\n\u003cp\u003eThe 1\/4\" NPT connection is larger than the 1\/8\" NPT used on the AFD1 (Watts bowl series). This is not interchangeable — thread size and bowl geometry are matched to the specific THB bowl design. Using the wrong drain on a bowl will result in a poor seal or incorrect float actuation. If you have THB bowls, use the AFD3. If you have standard Castair filter bowls (not THB series), use the AFD1.\u003c\/p\u003e\n\n\u003ch2\u003eKey Features\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eTHB Bowl-Specific Design:\u003c\/strong\u003e Direct-fit for Castair THB-series filter bowls — correct thread size, correct float geometry, no adapters needed\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e1\/4\" NPT Connection:\u003c\/strong\u003e Matches the drain port on THB-series bowls; not interchangeable with AFD1 (1\/8\" NPT)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFloat-Operated Automatic Drain:\u003c\/strong\u003e Mechanical float evacuates condensate automatically as it accumulates — no electricity, no timer\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePassive Mechanical Operation:\u003c\/strong\u003e No consumable electronic components, no power supply, no scheduled maintenance cycles to program\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eContinuous Bowl Protection:\u003c\/strong\u003e Drains in response to actual condensate accumulation, not a fixed time interval\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePrevents Filter Overflow:\u003c\/strong\u003e Keeps THB bowls within capacity so they continue to filter effectively\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSimple Thread-In Installation:\u003c\/strong\u003e Replaces the existing manual drain fitting on the THB bowl drain port\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCast Air Build Quality:\u003c\/strong\u003e Manufactured in Minnesota to Castair's standard for shop-environment reliability\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eWhy This Matters in a Working Shop\u003c\/h2\u003e\n\u003cp\u003eInline filter bowls do their job by pulling moisture out of the compressed air stream. The condensate has to go somewhere — it collects in the bowl. In a high-usage shop or in humid conditions, a THB bowl can fill up in a matter of hours. Once the bowl is at capacity, moisture carries over downstream.\u003c\/p\u003e\n\u003cp\u003eThe downstream effects are well known to anyone who has dealt with them: fisheye and blushing in spray finishes, rust in air tool internals, erratic operation in pneumatic controls, and deterioration of air hose interiors. None of these failures are dramatic or sudden — they accumulate over time as moisture does slow, consistent damage. The AFD3 prevents that accumulation from happening by keeping the bowl clear automatically.\u003c\/p\u003e\n\n\u003ch2\u003eWhat's in the Box\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e1x Cast Air AFD3 THB bowl float drain valve\u003c\/li\u003e\n  \u003cli\u003e1\/4\" NPT thread fitting for THB-series Castair filter bowl drain ports\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eAvailable Configurations\u003c\/h2\u003e\n\u003cp\u003eCast Air offers two bowl float drain options. Bowl series determines which part you need:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eAFD3 — $47.74 (this part):\u003c\/strong\u003e THB Bowl float drain. 1\/4\" NPT connection. Fits Castair THB-series filter bowls specifically. The lower-cost option of the two bowl drain valves.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eAFD1 — $77.77:\u003c\/strong\u003e Watts Bowl float drain. 1\/8\" NPT connection. Fits all standard Castair filter bowls (non-THB series). If you are unsure which bowl series you have, call us and we will confirm.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eFor automatic draining of the receiver tank itself (not a filter bowl), see the air-operated tank drain valves:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eADVS — $119.43:\u003c\/strong\u003e Air-operated tank drain valve only, for 1–10 HP compressors\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eADVSM — $154.00:\u003c\/strong\u003e Same valve with complete installation kit (strainer, shut-off, hardware)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eWhen Does a Shop Need the AFD3\u003c\/h2\u003e\n\u003cp\u003e\u003cstrong\u003eChoose the AFD3 when:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eYou have Castair THB-series filter bowls that currently require manual draining\u003c\/li\u003e\n  \u003cli\u003eYou are upgrading from the manual drain petcock on existing THB filter assemblies\u003c\/li\u003e\n  \u003cli\u003eYour THB bowls are in a high-humidity environment or on a high-demand air line where condensate accumulates quickly\u003c\/li\u003e\n  \u003cli\u003eYou want automatic bowl draining at the lowest cost — the AFD3 is $30 less than the AFD1\u003c\/li\u003e\n  \u003cli\u003eYou are installing new THB filters and want automatic drainage from day one\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eChoose the AFD1 instead when:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eYour filter bowls are standard Castair bowls, not the THB series — the AFD1 fits Watts-style bowls with 1\/8\" NPT drain ports\u003c\/li\u003e\n  \u003cli\u003eYou are unsure of your bowl series: call us at 866-217-0063 and we will confirm the right part before you order\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eNote:\u003c\/strong\u003e Neither the AFD3 nor the AFD1 mounts on or drains the compressor receiver tank. For tank drain automation, use the ADVS or ADVSM.\u003c\/p\u003e\n\n\u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePart Number:\u003c\/strong\u003e AFD3\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eManufacturer:\u003c\/strong\u003e Cast Air (Castair), Minnesota\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eType:\u003c\/strong\u003e Bowl float drain valve — automatic, mechanical\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eConnection Size:\u003c\/strong\u003e 1\/4\" NPT\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCompatible Bowl Series:\u003c\/strong\u003e Castair THB-series filter bowls\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eOperation:\u003c\/strong\u003e Mechanical float — no electricity required\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDrain Trigger:\u003c\/strong\u003e Float-activated when condensate reaches threshold level in bowl\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePrice:\u003c\/strong\u003e $47.74\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCountry of Origin:\u003c\/strong\u003e USA (Minnesota)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eWhy Buy From Air Compressor Factory Direct?\u003c\/h2\u003e\n\u003cp\u003eAir Compressor Factory Direct has been a Castair specialist since 2016. We stock the full Cast Air filter and drain accessory line because shops need more than just the compressor — they need the parts to keep the whole air system working correctly. The AFD3 is one of those parts that is easy to overlook until a filter bowl overfills and ruins a paint job or accelerates tool wear.\u003c\/p\u003e\n\u003cp\u003eIf you are not certain whether your filter bowls are THB series or standard Castair, call us. We will identify the correct drain from your filter part number and get you the right part the first time. Every order ships free. Full manufacturer warranty. No guessing, no returns for the wrong part.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCall 866-217-0063 for quick answers and help!\u003c\/strong\u003e\u003c\/p\u003e","brand":"Cast Air","offers":[{"title":"Default Title","offer_id":53342513529045,"sku":"AFD3","price":88.04,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0622\/8466\/0949\/files\/DRAINS-3.jpg?v=1772652565","url":"https:\/\/aircompressorfactorydirect.com\/products\/castair-thb-bowl-float-drain-afd3","provider":"Air Compressor Factory Direct","version":"1.0","type":"link"}