{"product_id":"castair-20hp-industrial-series-reciprocating-air-compressor-120-gallon-horizontal-i20324hc4z-s","title":"Castair 20HP Industrial Series Reciprocating Air Compressor 120 Gallon Horizontal I20324HC4Z-S","description":"\u003ch2\u003eCastair I20324HC4Z-S: 20HP 3-Phase Industrial Reciprocating Air Compressor — 240 Gallon Horizontal with Mounted Starter\u003c\/h2\u003e\n\n\u003cp\u003eThe Castair I20324HC4Z-S is a 20-horsepower, 3-phase, 240-gallon horizontal industrial reciprocating air compressor. Built around the C4 cast iron pump and priced at 2,542, this is a serious production compressor for multi-bay shops, body shops with active spray booths, or any industrial operation where consistent high-volume air supply is not optional.\u003c\/p\u003e\n\n\u003cp\u003eThe 240-gallon horizontal tank is the defining feature of this configuration. At 92.8 CFM free air delivery and 72 CFM at 175 PSI, the 20HP C4 pump can supply 5-7 simultaneous tool workstations. The 240-gallon tank provides the storage buffer that makes this practical in real-world shop conditions — where 3 technicians might all reach for their air guns at the same moment, or where a spray booth cycles through heavy demand periods. More tank means fewer compressor cycles per hour, which means less heat cycling of the pump and motor, which means longer service life.\u003c\/p\u003e\n\n\u003cp\u003eThe Z suffix indicates a factory-mounted magnetic motor starter. For a 3-phase unit at this power level, having the starter factory-mounted saves installation time, ensures proper electrical assembly, and simplifies the job for your electrician — they connect to a single panel rather than sourcing and mounting a separate starter enclosure.\u003c\/p\u003e\n\n\u003ch2\u003eC4 Pump — Engineering Details\u003c\/h2\u003e\n\n\u003ch3\u003eWhy the C4 Pump Matters\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePump designation:\u003c\/strong\u003e C4 — Two-stage, V4 cylinder configuration\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRated HP range:\u003c\/strong\u003e 15-25HP — this pump is built for the 20HP application, not working at its upper limit\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePump RPM:\u003c\/strong\u003e 519 — extremely slow for a reciprocating compressor; most comparable units run 800-1,200 RPM\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCylinder arrangement:\u003c\/strong\u003e V4 — four cylinders in a V configuration for better balance and smooth operation\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOil capacity:\u003c\/strong\u003e 1 gallon\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAll cast iron construction:\u003c\/strong\u003e Cylinders, heads, valve plates, crankcase — no aluminum in the compression path\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTapered roller bearings\u003c\/strong\u003e at both crankshaft ends for superior load handling and reduced friction wear\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePrecision steel connecting rods\u003c\/strong\u003e with automotive-type rod insert bearings — engineered for continuous-duty operation\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDisc and spring valves\u003c\/strong\u003e for high efficiency and field serviceability — replaceable without specialized tools\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e4-ring pistons\u003c\/strong\u003e for maximum efficiency and minimal oil carry-over\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCentrifugal unloader\u003c\/strong\u003e — ensures the pump starts unloaded every time, protecting the motor from startup torque overload\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eTank and Frame\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eTank capacity:\u003c\/strong\u003e 240 gallons, horizontal configuration\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTank dimensions:\u003c\/strong\u003e 90 x 39 x 70 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTank construction:\u003c\/strong\u003e Powder-coated ASME-rated steel with channel saddle frame\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSafety valve:\u003c\/strong\u003e ASME-rated, factory installed and sized for this unit\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBelt guard:\u003c\/strong\u003e Totally enclosed metal construction\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDischarge lines:\u003c\/strong\u003e Copper tubing or stainless-steel braided flex line\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eMotor and Electrical\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eHorsepower:\u003c\/strong\u003e 20HP\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePhase:\u003c\/strong\u003e 3-phase — requires proper 3-phase electrical service\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMotor speed:\u003c\/strong\u003e 1725 RPM industrial\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eService factor:\u003c\/strong\u003e 15% minimum\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMotor starter:\u003c\/strong\u003e Factory-mounted magnetic motor starter (Z designation) — properly sized for the motor\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMax working pressure:\u003c\/strong\u003e 175 PSI\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003ePerformance Specifications\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eMotor output:\u003c\/strong\u003e 20 HP\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eElectrical:\u003c\/strong\u003e 3-phase with factory-mounted magnetic starter\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTank capacity:\u003c\/strong\u003e 240 gallons, horizontal\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePump:\u003c\/strong\u003e C4 (Two-stage, V4)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePump RPM:\u003c\/strong\u003e 519\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFree air delivery (0 PSI):\u003c\/strong\u003e 92.8 CFM\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDelivery at 175 PSI:\u003c\/strong\u003e 72 CFM\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMax pressure:\u003c\/strong\u003e 175 PSI\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDimensions (LxWxH):\u003c\/strong\u003e 90 x 39 x 70 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 1,700 lbs\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePrice:\u003c\/strong\u003e 2,542\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eWhat's in the Box\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eCastair I20324HC4Z-S compressor — fully assembled on 240-gallon horizontal tank\u003c\/li\u003e\n\u003cli\u003eFactory-mounted magnetic motor starter (Z designation)\u003c\/li\u003e\n\u003cli\u003eASME safety valve (factory installed)\u003c\/li\u003e\n\u003cli\u003ePressure switch with unloader\u003c\/li\u003e\n\u003cli\u003eTotally enclosed metal belt guard\u003c\/li\u003e\n\u003cli\u003eCopper discharge and unloader tubing (or stainless braided flex line)\u003c\/li\u003e\n\u003cli\u003eOwner's documentation\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cem\u003eAftercooler is available as factory option (BGAC3M — for 20HP and up). Electrical connection to 3-phase service is performed by the customer's licensed electrician.\u003c\/em\u003e\u003c\/p\u003e\n\n\u003ch2\u003eAvailable Configurations — 20HP Industrial Series\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eI20312HC4Z-S:\u003c\/strong\u003e 20HP, 3-phase, 120gal Horizontal, C4 pump, 519 RPM, 72 CFM @ 175 PSI — same pump, smaller tank\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eI20324HC4Z-S (this unit):\u003c\/strong\u003e 20HP, 3-phase, 240gal Horizontal, C4 pump, 519 RPM, 72 CFM @ 175 PSI, 90x39x70, 1,700 lbs — double the tank storage\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eThe pump, motor, and CFM output are identical between the 120-gallon and 240-gallon versions. You are buying more air storage. In a shop with consistent demand from multiple simultaneous users, the 240-gallon tank reduces compressor cycling frequency, which extends pump and motor life. It also means faster pressure recovery after a heavy draw-down — important when you are running back-to-back vehicles through a spray booth.\u003c\/p\u003e\n\n\u003ch2\u003eWhen Does a Shop Need This vs. Stepping Up or Down?\u003c\/h2\u003e\n\n\u003ch3\u003eThis unit is right if:\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eYou are running 5-7 simultaneous technician workstations on pneumatic tools\u003c\/li\u003e\n\u003cli\u003eYou have an active spray booth consuming 30-50 CFM plus additional shop air demand\u003c\/li\u003e\n\u003cli\u003eYou have 3-phase electrical service available\u003c\/li\u003e\n\u003cli\u003eYou need the 240-gallon tank to buffer high-demand spikes or back-to-back heavy use\u003c\/li\u003e\n\u003cli\u003eA factory-mounted starter simplifies your installation or code requirements\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eStep down to the 120-gallon (I20312HC4Z-S) if:\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eYour shop footprint cannot accommodate the 90-inch length of the 240-gallon tank, and your demand profile is steady enough that the smaller tank storage is adequate\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eStep up to the 25HP (I25324HC4Z-S) if:\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eYour continuous demand exceeds 72 CFM at 175 PSI — the 25HP delivers 90 CFM from the same C4 pump platform\u003c\/li\u003e\n\u003cli\u003eYou are running sandblasting equipment, large plasma systems, or other continuous-high-CFM processes alongside general shop air\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eConsider the 15HP if:\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eYour operation is 3-4 technicians on standard shop tools without spray booth demands — the I15312HC3-S at 50.2 CFM handles that at lower operating cost\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eWhy Buy From Air Compressor Factory Direct?\u003c\/h2\u003e\n\u003cp\u003eWe have been selling industrial air compressors and shop equipment since 2016. At this price and weight class, you want to talk to someone before you order. We can help you verify your electrical service is adequate, confirm the footprint fits your installation space, and advise on the aftercooler option based on your application. A compressor this size is a long-term capital equipment decision — we take that seriously.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFree shipping\u003c\/strong\u003e to commercial addresses in the lower 48 states (freight delivery — requires loading dock or forklift)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFree tech support\u003c\/strong\u003e at 866-217-0063 before and after your purchase\u003c\/li\u003e\n\u003cli\u003e\u003cstrong\u003eFull Castair manufacturer warranty\u003c\/strong\u003e\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHonest buying guidance\u003c\/strong\u003e — we will tell you if this is sized correctly for your application\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAuthorized dealer\u003c\/strong\u003e with direct Castair factory access\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cstrong\u003eCall 866-217-0063 for quick answers and help!\u003c\/strong\u003e\u003c\/p\u003e\n\n\u003cdiv class=\"product-faq\"\u003e\n\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\n\u003cdiv class=\"faq-item\"\u003e\n\u003ch3\u003eWhat is the duty cycle on the I20324HC4Z-S, and can it run continuously in a production environment?\u003c\/h3\u003e\n\u003cp\u003eThe Cast Air I20324HC4Z-S is rated for 100% duty cycle at full load — this is a direct result of the all-cast-iron construction on the pump cylinders, heads, and crankcase. Cast iron dissipates heat far better than aluminum, so the pump doesn't need mandatory cool-down cycles the way lighter-duty compressors do. For continuous-demand shops like auto body, sandblasting, or manufacturing lines, this is the right spec.\u003c\/p\u003e\n\u003c\/div\u003e\n\n\u003cdiv class=\"faq-item\"\u003e\n\u003ch3\u003eWhat oil does the I20324HC4Z-S take, and how often does it need to be changed?\u003c\/h3\u003e\n\u003cp\u003eCast Air specifies a non-detergent 30-weight compressor oil (SAE 30) — do not use motor oil, as the detergent additives break down ring seals over time. Oil change interval is every 500 hours under normal conditions, or annually if hours are lower. Check the sight glass daily at startup; the all-cast-iron pump runs tighter tolerances than aluminum units, so keeping clean oil in it is the single biggest factor in pump longevity.\u003c\/p\u003e\n\u003c\/div\u003e\n\n\u003cdiv class=\"faq-item\"\u003e\n\u003ch3\u003eWhy does this 20 HP model require 3-phase power instead of single-phase?\u003c\/h3\u003e\n\u003cp\u003eAt 20 HP, the starting amperage draw on single-phase would exceed 100 amps, which trips breakers and stresses wiring in most shop electrical systems. Three-phase power distributes the load across three legs, drops the starting current significantly, and runs the motor cooler and more efficiently under sustained load. If your shop only has single-phase service, you'd need a phase converter — call us at 866-217-0063 and we can walk through whether that setup makes sense for your application versus bringing in 3-phase, which is the cleaner solution at this HP rating.\u003c\/p\u003e\n\u003c\/div\u003e\n\n\u003cdiv class=\"faq-item\"\u003e\n\u003ch3\u003eIs a 240-gallon horizontal tank enough for a busy production shop, or will the compressor short-cycle?\u003c\/h3\u003e\n\u003cp\u003eAt 20 HP, the I20324HC4Z-S typically produces in the range of 80–85 CFM at 175 PSI — the 240-gallon tank gives you substantial reserve to handle burst demand from multiple tools without the pump cycling on every trigger pull. For most shops running 3–5 air tools simultaneously (impact wrenches, DA sanders, air ratchets), the 240-gallon tank is well-matched to this pump output. If you're running continuous high-CFM equipment like large spray booths or multiple plasma cutters simultaneously, total demand calculation against rated CFM is the deciding factor, not tank size alone.\u003c\/p\u003e\n\u003c\/div\u003e\n\n\u003cdiv class=\"faq-item\"\u003e\n\u003ch3\u003eWhat size shop or operation is the I20324HC4Z-S designed for?\u003c\/h3\u003e\n\u003cp\u003eThis unit is sized for mid-to-large commercial shops — think 8-to-15-bay automotive service centers, body shops running two or more spray guns simultaneously, fabrication shops with welding and grinding demand, or light manufacturing lines. The 20 HP motor and 240-gallon horizontal tank handle the kind of multi-shift, multi-tool environments where a 5–10 HP compressor would be running non-stop. Cast Air has been building these all-cast-iron units in Spicer, MN since 1991, and the I20324HC4Z-S is their workhorse spec for exactly this class of shop.\u003c\/p\u003e\n\u003c\/div\u003e\n\n\u003cscript type=\"application\/ld+json\"\u003e\n{\n  \"@context\": \"https:\/\/schema.org\",\n  \"@type\": \"FAQPage\",\n  \"mainEntity\": [\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What is the duty cycle on the I20324HC4Z-S, and can it run continuously in a production environment?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"The Cast Air I20324HC4Z-S is rated for 100% duty cycle at full load — this is a direct result of the all-cast-iron construction on the pump cylinders, heads, and crankcase. Cast iron dissipates heat far better than aluminum, so the pump doesn't need mandatory cool-down cycles the way lighter-duty compressors do. For continuous-demand shops like auto body, sandblasting, or manufacturing lines, this is the right spec.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What oil does the I20324HC4Z-S take, and how often does it need to be changed?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Cast Air specifies a non-detergent 30-weight compressor oil (SAE 30) — do not use motor oil, as the detergent additives break down ring seals over time. Oil change interval is every 500 hours under normal conditions, or annually if hours are lower. Check the sight glass daily at startup; the all-cast-iron pump runs tighter tolerances than aluminum units, so keeping clean oil in it is the single biggest factor in pump longevity.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Why does this 20 HP model require 3-phase power instead of single-phase?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"At 20 HP, the starting amperage draw on single-phase would exceed 100 amps, which trips breakers and stresses wiring in most shop electrical systems. Three-phase power distributes the load across three legs, drops the starting current significantly, and runs the motor cooler and more efficiently under sustained load. If your shop only has single-phase service, you'd need a phase converter — call us at 866-217-0063 and we can walk through whether that setup makes sense for your application versus bringing in 3-phase, which is the cleaner solution at this HP rating.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Is a 240-gallon horizontal tank enough for a busy production shop, or will the compressor short-cycle?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"At 20 HP, the I20324HC4Z-S typically produces in the range of 80–85 CFM at 175 PSI — the 240-gallon tank gives you substantial reserve to handle burst demand from multiple tools without the pump cycling on every trigger pull. For most shops running 3–5 air tools simultaneously (impact wrenches, DA sanders, air ratchets), the 240-gallon tank is well-matched to this pump output. If you're running continuous high-CFM equipment like large spray booths or multiple plasma cutters simultaneously, total demand calculation against rated CFM is the deciding factor, not tank size alone.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What size shop or operation is the I20324HC4Z-S designed for?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"This unit is sized for mid-to-large commercial shops — think 8-to-15-bay automotive service centers, body shops running two or more spray guns simultaneously, fabrication shops with welding and grinding demand, or light manufacturing lines. The 20 HP motor and 240-gallon horizontal tank handle the kind of multi-shift, multi-tool environments where a 5–10 HP compressor would be running non-stop. Cast Air has been building these all-cast-iron units in Spicer, MN since 1991, and the I20324HC4Z-S is their workhorse spec for exactly this class of shop.\"\n      }\n    }\n  ]\n}\n\u003c\/script\u003e\n\u003c\/div\u003e","brand":"Cast Air","offers":[{"title":"Default Title","offer_id":53342561501397,"sku":"I20324HC4Z-S","price":22332.34,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0622\/8466\/0949\/files\/I30324HC4Z-S.jpg?v=1772652709","url":"https:\/\/aircompressorfactorydirect.com\/products\/castair-20hp-industrial-series-reciprocating-air-compressor-120-gallon-horizontal-i20324hc4z-s","provider":"Air Compressor Factory Direct","version":"1.0","type":"link"}