{"product_id":"345-viton-o-ring-75a-durometer-4in-id-4-3-8in-od-reliable-chemical","title":"345 Viton O-Ring 75A Durometer 4in ID 4-3\/8in OD - Reliable Chemical","description":"\u003cp\u003eIn this review the 345 Viton O-Ring is presented as a practical replacement seal for industrial, hydraulic and fuel-handling applications; its chief selling point is chemical and heat resistance thanks to the Viton compound. For technicians, hobbyists and maintenance staff who need an O-ring that holds up to high temperatures and many fuels, this pack of 10 provides consistency of size and material. The review focuses on fit, material performance and typical use cases based on customer feedback and the product specification.\u003c\/p\u003e\n\u003ch2\u003eKey Features\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Made of Viton fluorocarbon elastomer to resist fuels, oils and many chemicals for longer service life.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTemperature range:\u003c\/strong\u003e Rated from -15 degrees F to 400 degrees F so it performs across cold starts and high-heat operating environments.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDurometer:\u003c\/strong\u003e 75A hardness provides good resistance to penetration and reliable compression set for sealing cylindrical surfaces.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eForm factor:\u003c\/strong\u003e Round cross-section designed to seal between overlapping cylindrical parts without custom machining.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStandards:\u003c\/strong\u003e Manufactured to meet Aerospace Standard AS568A sizing conventions for predictable interchangeability.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2\u003eWho It's For\u003c\/h2\u003e\n\u003cp\u003eThis O-ring pack is best for maintenance technicians, machinists and end users who need a small stock of correctly sized seals for fuel bottles, firearm components, vacuum fittings or hydraulic assemblies. The chemical compatibility and wide temperature allowance make it suitable for non-flammable hydraulic fuels, silicone oils, aromatic and aliphatic hydrocarbons, and many workshop environments.\u003c\/p\u003e\n\u003cp\u003eThose who should look elsewhere include users needing resistance to low molecular organic acids, ammonia gas, alkalis, amines, glycol-based brake fluids or continuous exposure to super-heated steam, since Viton can be vulnerable to those agents. Also, if a softer shore hardness than 75A is required for delicate low-pressure seals, pick a different durometer.\u003c\/p\u003e\n\u003ch2\u003ePros \u0026amp; Cons\u003c\/h2\u003e\n\u003cp\u003e\u003cstrong\u003ePros\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eExcellent heat and fuel resistance, making it reliable in high-temperature or fuel-exposed applications.\u003c\/li\u003e\n\u003cli\u003eConsistent sizing and fit that customers report working well for MSA fuel bottle seals and Remington barrel seals.\u003c\/li\u003e\n\u003cli\u003eGood value in a pack of 10 for replacements and preventive maintenance spares.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eCons\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eNot compatible with certain chemicals such as ammonia, strong alkalis, amines or glycol-based brake fluids, limiting use in some specialty fluids.\u003c\/li\u003e\n\u003cli\u003e75A hardness may be too firm for some low-pressure or delicate sealing needs where a softer compound is preferred.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2\u003eSpecifications\u003c\/h2\u003e\n\u003ctable\u003e\n\u003ctr\u003e\n\u003ctd\u003eMaterial\u003c\/td\u003e\n\u003ctd\u003eViton (fluorocarbon elastomer)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eColor\u003c\/td\u003e\n\u003ctd\u003eBlack\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eInner diameter (ID)\u003c\/td\u003e\n\u003ctd\u003e4 in\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOuter diameter (OD)\u003c\/td\u003e\n\u003ctd\u003e4-3\/8 in\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCross-section \/ Width\u003c\/td\u003e\n\u003ctd\u003e3\/16 in\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDurometer\u003c\/td\u003e\n\u003ctd\u003e75A\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTemperature range\u003c\/td\u003e\n\u003ctd\u003e-15 degrees F to 400 degrees F\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\n\u003ch2\u003eOur Verdict\u003c\/h2\u003e\n\u003cp\u003eThe 345 Viton O-Ring pack is a solid, no-nonsense choice for anyone who needs chemical and heat-resistant seals in standard AS568A sizes. It is particularly good value for spares and repairs where fuel and high temperature exposure are expected, though users with compatibility concerns for specific chemicals or who need a softer compound should choose an alternative.\u003c\/p\u003e\n\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\n\u003cp\u003e\u003cstrong\u003eAre these O-rings compatible with gasoline and diesel?\u003c\/strong\u003e\u003cbr\u003eYes; Viton is compatible with many fuels and aromatic and aliphatic hydrocarbons, making these O-rings suitable for typical gasoline and diesel exposure.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWill the 75A hardness work for firearm seals and switches?\u003c\/strong\u003e\u003cbr\u003eCustomers report good fit and functionality for Remington 1100 barrel seals and Silencerco switchback applications, but performance depends on the specific seal design and compression required.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I use these in brake fluid systems?\u003c\/strong\u003e\u003cbr\u003eNo; Viton is vulnerable to glycol-based brake fluids, so do not use these O-rings where constant contact with such fluids is expected.\u003c\/p\u003e","brand":"Mr O-Ring","offers":[{"title":"Default Title","offer_id":48666056098011,"sku":"B000FMUX78","price":46.19,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0724\/1043\/1707\/files\/81iyYJCP7YL._SL1500_2efc431a-726c-4a01-b940-5ccf144c6e2a.jpg?v=1778626405","url":"https:\/\/gearmusthave.com\/products\/345-viton-o-ring-75a-durometer-4in-id-4-3-8in-od-reliable-chemical","provider":"GearMustHave","version":"1.0","type":"link"}