{"title":"Welch WOB-L Dry Piston Vacuum Pumps","description":"\u003cp\u003e\u003ca href=\"https:\/\/www.provac.com\/collections\/welch\" title=\"Welch Vacuum Pumps\" style=\"font-family: 'Open Sans', sans-serif; font-size: 14px; letter-spacing: .5px; font-weight: 400; color: #23527c;\"\u003eWelch\u003c\/a\u003e WOB-L pumps are oil-free piston pumps that give rough vacuum, pressure or both from one compact unit. With no oil in the pump, there is nothing to change, nothing to contaminate your sample and no oil mist at the exhaust.\u003c\/p\u003e\n\u003cp style=\"margin-top: 12px;\"\u003eWOB-L pumps are found on lab benches, in medical and analytical instruments and in field sampling equipment because they are small, simple and run for years with little care. At Provac Sales, we supply Welch WOB-L pumps new and rebuilt, and we service them in our own shop.\u003c\/p\u003e\n\n\u003ch3 style=\"margin-top: 24px;\"\u003eWelch Dry Pump Models We Carry\u003c\/h3\u003e\n\u003ch4 style=\"margin-top: 16px;\"\u003eSmall WOB-L Pumps\u003c\/h4\u003e\n\u003cul\u003e\n\u003cli\u003eWelch 2511, the smallest WOB-L, sold as a bare pump and as the 2511-75 aspiration system\u003c\/li\u003e\n\u003cli\u003eWelch 2515, offered as a complete aspiration station\u003c\/li\u003e\n\u003cli\u003eWelch 2522, a compact dry piston pump for vacuum and pressure\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch4 style=\"margin-top: 16px;\"\u003eMid-Size WOB-L Pumps\u003c\/h4\u003e\n\u003cul\u003e\n\u003cli\u003eWelch 2534, about 1.2 CFM with vacuum to about 70 Torr\u003c\/li\u003e\n\u003cli\u003eWelch 2546, a vacuum and pressure pump for filtration and sampling\u003c\/li\u003e\n\u003cli\u003eWelch 2562, a higher-flow single-head pump\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch4 style=\"margin-top: 16px;\"\u003eHigh-Flow WOB-L Pumps\u003c\/h4\u003e\n\u003cul\u003e\n\u003cli\u003eWelch 2561 and 2567, twin-head pumps for faster pumpdown\u003c\/li\u003e\n\u003cli\u003eWelch 2581, about 3.5 CFM, the largest-flow WOB-L\u003c\/li\u003e\n\u003cli\u003eWelch 2585, a twin-head pump for deeper vacuum\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch4 style=\"margin-top: 16px;\"\u003ePortable Pumps\u003c\/h4\u003e\n\u003cul\u003e\n\u003cli\u003eWelch 2050 and 2060 compact pumps, including DC versions for portable use\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eMany listings are rebuilt units. Some show a price and others are quote-based. Each product page lists free air flow, vacuum, pressure rating and voltage.\u003c\/p\u003e\n\n\u003ch3 style=\"margin-top: 24px;\"\u003eVacuum, Pressure and Twin-Head Models\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eSingle-head WOB-L pumps are the simplest choice for light vacuum or pressure. They suit aspiration, sampling and small filtration setups.\u003c\/li\u003e\n\u003cli\u003eTwin-head pumps, such as the 2561, 2567 and 2581, add flow or depth. Heads can run in parallel for more flow, or in series for deeper vacuum, depending on the model.\u003c\/li\u003e\n\u003cli\u003eMany WOB-L pumps can supply pressure from the exhaust side as well as vacuum at the inlet. Check the pressure rating on the product page before using a pump as a compressor.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3 style=\"margin-top: 24px;\"\u003eHow a WOB-L Piston Pump Works\u003c\/h3\u003e\n\u003cp\u003eWOB-L stands for wobble piston. The piston is fixed rigidly to a connecting rod that rides on an eccentric on the motor shaft. As the shaft turns, the piston moves up and down and rocks slightly in the cylinder.\u003c\/p\u003e\n\u003cp style=\"margin-top: 12px;\"\u003eA flexible cup seal on the piston keeps the cylinder sealed through that rocking motion. On the down stroke, gas enters through the inlet valve. On the up stroke, it is compressed and pushed out through the exhaust valve.\u003c\/p\u003e\n\u003cp style=\"margin-top: 12px;\"\u003eThe bearings are sealed, so no oil is needed anywhere in the pump.\u003c\/p\u003e\n\n\u003ch3 style=\"margin-top: 24px;\"\u003eKey Features\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eCompletely oil-free, with no oil changes and no oil mist\u003c\/li\u003e\n\u003cli\u003eVacuum and pressure from one pump on many models\u003c\/li\u003e\n\u003cli\u003eCompact, light and easy to build into instruments\u003c\/li\u003e\n\u003cli\u003eLong-life piston cup seals and valves\u003c\/li\u003e\n\u003cli\u003eSingle- and twin-head designs for more flow or deeper vacuum\u003c\/li\u003e\n\u003cli\u003eAspiration and filtration stations available ready to use\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3 style=\"margin-top: 24px;\"\u003eApplications for Welch WOB-L Dry Pumps\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eVacuum filtration and aspiration\u003c\/li\u003e\n\u003cli\u003eAir and gas sampling, including environmental monitoring\u003c\/li\u003e\n\u003cli\u003eMedical and analytical instruments\u003c\/li\u003e\n\u003cli\u003eGel dryers, desiccators and degassing\u003c\/li\u003e\n\u003cli\u003eLab air supply for pressure filtration and agitation\u003c\/li\u003e\n\u003cli\u003eVacuum pick-and-place and holding fixtures\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3 style=\"margin-top: 24px;\"\u003eHow to Choose the Right Welch Dry Pump\u003c\/h3\u003e\n\u003cp\u003eBefore ordering, confirm:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eWhether you need vacuum, pressure or both\u003c\/li\u003e\n\u003cli\u003eThe vacuum level or pressure your process needs\u003c\/li\u003e\n\u003cli\u003eFree air flow for your flask, filter or instrument\u003c\/li\u003e\n\u003cli\u003eWhether liquid or vapor could reach the pump, so you can add a trap\u003c\/li\u003e\n\u003cli\u003eSupply voltage and frequency, or DC for portable use\u003c\/li\u003e\n\u003cli\u003eDuty cycle, continuous or intermittent\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3 style=\"margin-top: 24px;\"\u003eMaintenance Tips\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eReplace piston cup seals and valves at the interval in the manual or when performance drops\u003c\/li\u003e\n\u003cli\u003eUse a vacuum trap or filter flask so liquids never reach the pump\u003c\/li\u003e\n\u003cli\u003eKeep the inlet filter clean on dusty processes\u003c\/li\u003e\n\u003cli\u003eKeep the cooling fan and air paths clear\u003c\/li\u003e\n\u003cli\u003eDo not run a pressure model above its rated outlet pressure\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eWe stock service kits for common Welch WOB-L models.\u003c\/p\u003e\n\n\u003ch3 style=\"margin-top: 24px;\"\u003eSigns Your WOB-L Pump Needs Service\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eThe pump no longer reaches its rated vacuum or pressure\u003c\/li\u003e\n\u003cli\u003eLonger pumpdown on your filter flask or sample line\u003c\/li\u003e\n\u003cli\u003eSquealing or knocking, which can mean worn bearings\u003c\/li\u003e\n\u003cli\u003eThe motor runs hot or trips its thermal protection\u003c\/li\u003e\n\u003cli\u003eLiquid or debris has entered the pump\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3 style=\"margin-top: 24px;\"\u003eNew vs Rebuilt Welch WOB-L Pumps\u003c\/h3\u003e\n\u003cp\u003eWOB-L pumps are simple, so a rebuild restores most of their original performance. A rebuild usually includes new piston cups, valves and gaskets, a bearing check and a performance test for vacuum and pressure.\u003c\/p\u003e\n\u003cp style=\"margin-top: 12px;\"\u003eA rebuilt pump is a cost-effective way to replace a pump built into an instrument without changing the mounting or connections.\u003c\/p\u003e\n\n\u003ch3 style=\"margin-top: 24px;\"\u003eWelch Dry Pumps Repair\u003c\/h3\u003e\n\u003cp\u003eProvac Sales repairs and rebuilds Welch WOB-L dry piston pumps, including seal and valve replacement. Submit an \u003ca href=\"https:\/\/www.provac.com\/pages\/rma\" title=\"RMA Request\" style=\"font-family: 'Open Sans', sans-serif; font-size: 14px; letter-spacing: .5px; font-weight: 400; color: #23527c;\"\u003eRMA request\u003c\/a\u003e and complete the contamination data sheet before shipping. See our \u003ca href=\"https:\/\/www.provac.com\/pages\/pump-repair\" title=\"Vacuum Pump Repair\" style=\"font-family: 'Open Sans', sans-serif; font-size: 14px; letter-spacing: .5px; font-weight: 400; color: #23527c;\"\u003epump repair\u003c\/a\u003e page for more information.\u003c\/p\u003e\n\n\u003ch3 style=\"margin-top: 24px;\"\u003eRelated Welch Collections\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/www.provac.com\/collections\/welch-diaphragm-pumps\" title=\"Welch Diaphragm Pumps\" style=\"font-family: 'Open Sans', sans-serif; font-size: 14px; letter-spacing: .5px; font-weight: 400; color: #23527c;\"\u003eWelch diaphragm pumps\u003c\/a\u003e, chemistry-duty oil-free pumps for solvent work\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/www.provac.com\/collections\/welch-scroll-pumps\" title=\"Welch Scroll Pumps\" style=\"font-family: 'Open Sans', sans-serif; font-size: 14px; letter-spacing: .5px; font-weight: 400; color: #23527c;\"\u003eWelch scroll pumps\u003c\/a\u003e, SCSpro scroll pumps for deeper dry vacuum\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/www.provac.com\/collections\/welch-vane-pumps\" title=\"Welch Vane Pumps\" style=\"font-family: 'Open Sans', sans-serif; font-size: 14px; letter-spacing: .5px; font-weight: 400; color: #23527c;\"\u003eWelch vane pumps\u003c\/a\u003e, DuoSeal and CRVpro pumps for high vacuum\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"https:\/\/www.provac.com\/collections\/welch\" title=\"Welch Vacuum Pumps\" style=\"font-family: 'Open Sans', sans-serif; font-size: 14px; letter-spacing: .5px; font-weight: 400; color: #23527c;\"\u003eAll Welch vacuum pumps\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/www.provac.com\/collections\/dry-pumps\" title=\"Dry Vacuum Pumps\" style=\"font-family: 'Open Sans', sans-serif; font-size: 14px; letter-spacing: .5px; font-weight: 400; color: #23527c;\"\u003eAll dry pumps\u003c\/a\u003e from every brand we carry\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3 style=\"margin-top: 24px;\"\u003eFind the Right Welch WOB-L Dry Pump\u003c\/h3\u003e\n\u003cp\u003eSend us your application, required vacuum or pressure, flow, supply voltage and duty cycle. We will recommend the right Welch WOB-L pump, confirm new or rebuilt availability, or quote a rebuild of your existing pump.\u003c\/p\u003e\n\u003cp style=\"margin-top: 12px;\"\u003eBrowse our inventory above or \u003ca href=\"https:\/\/www.provac.com\/pages\/contact-1\" title=\"Contact Provac\" style=\"font-family: 'Open Sans', sans-serif; font-size: 14px; letter-spacing: .5px; font-weight: 400; color: #23527c;\"\u003econtact our vacuum specialists\u003c\/a\u003e at 831-462-8900.\u003c\/p\u003e\n\n\u003ch3 style=\"margin-top: 24px;\"\u003eWelch WOB-L Dry Pump FAQ\u003c\/h3\u003e\n\u003ch4 style=\"margin-top: 16px;\"\u003e1. What does WOB-L mean on a Welch pump?\u003c\/h4\u003e\n\u003cp\u003eWOB-L refers to the wobble piston design. The piston is fixed to its connecting rod and rocks slightly as it moves, with a flexible cup seal keeping the cylinder sealed. This removes the need for a wrist pin and oil.\u003c\/p\u003e\n\u003ch4 style=\"margin-top: 16px;\"\u003e2. Can a Welch WOB-L pump supply pressure as well as vacuum?\u003c\/h4\u003e\n\u003cp\u003eMany models can. The inlet gives vacuum and the exhaust gives pressure. Check the pressure rating on the product page and do not exceed it.\u003c\/p\u003e\n\u003ch4 style=\"margin-top: 16px;\"\u003e3. How deep a vacuum does a WOB-L pump reach?\u003c\/h4\u003e\n\u003cp\u003eWOB-L pumps give rough vacuum. A Welch 2534, for example, reaches about 70 Torr. Twin-head models go deeper. For lower pressures, choose a scroll or rotary vane pump.\u003c\/p\u003e\n\u003ch4 style=\"margin-top: 16px;\"\u003e4. Do Welch WOB-L pumps need oil?\u003c\/h4\u003e\n\u003cp\u003eNo. WOB-L pumps are oil-free. The bearings are sealed and the piston uses a dry cup seal.\u003c\/p\u003e\n\u003ch4 style=\"margin-top: 16px;\"\u003e5. Which Welch WOB-L pump is best for vacuum filtration?\u003c\/h4\u003e\n\u003cp\u003eA single-head pump such as the 2522 or 2546 handles most filtration setups. For several filter stations or faster flow, step up to a twin-head pump like the 2561 or 2581, and always use a trap to keep liquid out of the pump.\u003c\/p\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 does WOB-L mean on a Welch pump?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"WOB-L refers to the wobble piston design. The piston is fixed to its connecting rod and rocks slightly as it moves, with a flexible cup seal keeping the cylinder sealed. This removes the need for a wrist pin and oil.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Can a Welch WOB-L pump supply pressure as well as vacuum?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Many models can. The inlet gives vacuum and the exhaust gives pressure. Check the pressure rating on the product page and do not exceed it.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"How deep a vacuum does a WOB-L pump reach?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"WOB-L pumps give rough vacuum. A Welch 2534, for example, reaches about 70 Torr. Twin-head models go deeper. For lower pressures, choose a scroll or rotary vane pump.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Do Welch WOB-L pumps need oil?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"No. WOB-L pumps are oil-free. The bearings are sealed and the piston uses a dry cup seal.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Which Welch WOB-L pump is best for vacuum filtration?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"A single-head pump such as the 2522 or 2546 handles most filtration setups. For several filter stations or faster flow, step up to a twin-head pump like the 2561 or 2581, and always use a trap to keep liquid out of the pump.\"\n      }\n    }\n  ]\n}\n\u003c\/script\u003e","products":[{"product_id":"welch-2546-dry-diaphragm-pump","title":"Welch 2546 Dry Piston Pump","description":"\u003cdiv\u003e\n\u003cdiv id=\"tabs\"\u003e\n\u003cdiv class=\"tab active-tab\"\u003e\u003ca\u003eOverview\u003c\/a\u003e\u003c\/div\u003e\n\u003cdiv class=\"tab\"\u003e\u003ca\u003eSpecifications\u003c\/a\u003e\u003c\/div\u003e\n\u003cdiv class=\"tab\"\u003e\u003ca\u003eVideos\u003c\/a\u003e\u003c\/div\u003e\n\u003cdiv class=\"tab\"\u003e\u003ca\u003ePump Repair\u003c\/a\u003e\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv id=\"tab-contents\"\u003e\n\u003cdiv class=\"tab-content\"\u003e\n\u003cstrong\u003eType of product\u003c\/strong\u003e: piston pump\u003cbr\u003e\u003cstrong\u003eManufacturer\u003c\/strong\u003e: Welch\u003cbr\u003e\u003cstrong\u003eCondition\u003c\/strong\u003e: new\u003cbr\u003e\u003cstrong\u003ePrice\u003c\/strong\u003e: $978.00\u003cbr\u003e\u003cstrong\u003eInlet\u003c\/strong\u003e: 1\/4\" NPT\u003cbr\u003e\u003cstrong\u003eExhaust\u003c\/strong\u003e: 1\/4\" NPT\u003cbr\u003e\u003cstrong\u003eMotor\u003c\/strong\u003e: 1 Phase, 115V, 60Hz\u003cbr\u003e\u003cstrong\u003ePumping speed\u003c\/strong\u003e: 1.6 CFM (60Hz)\u003cbr\u003e\u003cstrong\u003eUltimate pressure\u003c\/strong\u003e: 60 Torr\u003cbr\u003e\u003cstrong\u003eWeight\u003c\/strong\u003e: 14 lbs\u003cbr\u003e*Other Configurations Available Upon Request\u003cbr\u003e\u003cstrong\u003eOUT OF STOCK ITEMS STILL AVAILABLE FOR PURCHASE, please contact\u003c\/strong\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"tab-content\"\u003e\n\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0598\/4021\/files\/2546.pdf?v=1679586425\" target=\"_blank\" title=\"Welch 2546 Technical Data Sheet\" rel=\"noopener noreferrer\"\u003eTechnical Sheet\u003c\/a\u003e\u003cbr\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0598\/4021\/files\/Welch_2522_2534_2546_Manual.pdf?v=1679586190\" target=\"_blank\" title=\"Welch 2546 Instruction Manual\" rel=\"noopener noreferrer\"\u003eManual\u003c\/a\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e","brand":"Vacuum Pumps - Provac Sales Inc.","offers":[{"title":"Default Title","offer_id":7707174019,"sku":null,"price":978.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0598\/4021\/products\/Welch_2546_1.jpg?v=1558472845"},{"product_id":"welch-scspro15-dry-scroll-pump-new","title":"Welch SCSpro15 Dry Scroll Pump, New","description":"\u003cdiv\u003e\n\u003cdiv id=\"tabs\"\u003e\n\u003cdiv class=\"tab active-tab\"\u003e\u003ca\u003eOverview\u003c\/a\u003e\u003c\/div\u003e\n\u003cdiv class=\"tab\"\u003e\u003ca\u003eSpecifications\u003c\/a\u003e\u003c\/div\u003e\n\u003cdiv class=\"tab\"\u003e\u003ca\u003eVideos\u003c\/a\u003e\u003c\/div\u003e\n\u003cdiv class=\"tab\"\u003e\u003ca\u003ePump Repair\u003c\/a\u003e\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv id=\"tab-contents\"\u003e\n\u003cdiv class=\"tab-content\"\u003e\n\u003cstrong\u003eType of product\u003c\/strong\u003e: scroll pump\u003cbr\u003e\u003cstrong\u003eManufacturer\u003c\/strong\u003e: Welch\u003cbr\u003e\u003cstrong\u003eCondition\u003c\/strong\u003e: new\u003cbr\u003e\u003cstrong\u003ePrice\u003c\/strong\u003e: Ask\u003cbr\u003e\u003cstrong\u003eInlet\u003c\/strong\u003e: KF25\u003cbr\u003e\u003cstrong\u003eExhaust\u003c\/strong\u003e: KF16\u003cbr\u003e\u003cstrong\u003eMotor\u003c\/strong\u003e: 1 Phase, 115V\/220-240V, 50\/60Hz\u003cbr\u003e\u003cstrong\u003ePumping speed\u003c\/strong\u003e: 9.9 CFM (60Hz)\u003cbr\u003e\u003cstrong\u003eUltimate pressure\u003c\/strong\u003e: 1.2 x 10−2 Torr\u003cbr\u003e\u003cstrong\u003eWeight\u003c\/strong\u003e: 66 lbs\u003cbr\u003e*Other Configurations Available Upon Request\u003cbr\u003e\u003cstrong\u003eOUT OF STOCK ITEMS STILL AVAILABLE FOR PURCHASE, please contact\u003c\/strong\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"tab-content\"\u003e\n\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0598\/4021\/files\/2023_11_Welch_B_SCpro15_Scroll.pdf?v=1773185675\" target=\"_blank\" title=\"Welch Scroll Vac Cut Sheet\" rel=\"noopener\"\u003eTechnical Sheet\u003c\/a\u003e\u003cbr\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0598\/4021\/files\/2023_11_Welch_B_SCpro15_Scroll.pdf?v=1773185675\" target=\"_blank\" title=\"Welch Scrollvac Cut Sheet\" rel=\"noopener\"\u003eManual\u003c\/a\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e","brand":"Vacuum Pumps - Provac Sales Inc.","offers":[{"title":"Default Title","offer_id":43802244743252,"sku":null,"price":5624.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0598\/4021\/files\/WelchSrollVac.png?v=1773185259"}],"url":"https:\/\/www.provac.com\/collections\/welch-dry-pumps.oembed","provider":"Provac","version":"1.0","type":"link"}