--- title: "Check Valves vs. Relief Valves: What’s the Difference?" description: "Check valves vs. relief valves: Learn how valve orientation and opening pressure determine function and how one valve can often serve both purposes." image: https://blog.smartproducts.com/hubfs/valve%20tops.jpg --- [Skip to content](https://blog.smartproducts.com/blog/check-valves-vs.-relief-valves-whats-the-difference#main-content) [![Smart Products](https://smartproducts.com/wp-content/uploads/2024/12/cropped-fullcolorlogo.png)](https://smartproducts.com/) - [Valves ▼](https://smartproducts.com/check-valves/) - [Pumps ▼](https://smartproducts.com/pumps/) - [Check Valve Operation](https://smartproducts.com/technical-resources/check-valve-operation/) - [Resources ▼](https://smartproducts.com/technical-resources/) - [About ▼](https://smartproducts.com/about/) - [Industries Served ▼](https://smartproducts.com/industries-served/) - [Contact](https://smartproducts.com/contact-us/) [![Smart Products](https://smartproducts.com/wp-content/uploads/2024/12/cropped-fullcolorlogo.png)](https://smartproducts.com/) - [Valves ▼](https://smartproducts.com/check-valves/) - [Pumps ▼](https://smartproducts.com/pumps/) - [Check Valve Operation](https://smartproducts.com/technical-resources/check-valve-operation/) - [Resources ▼](https://smartproducts.com/technical-resources/) - [About ▼](https://smartproducts.com/about/) - [Industries Served ▼](https://smartproducts.com/industries-served/) - [Contact](https://smartproducts.com/contact-us/) This is a search field with an auto-suggest feature attached. - There are no suggestions because the search field is empty. # Check Valves vs. Relief Valves: What’s the Difference? [Smart Products](https://blog.smartproducts.com/blog/author/smart-products) Oct 16, 2026, 10:27:28 AM No quod sanctus instructior ius, et intellegam interesset duo. Vix cu nibh gubergren dissentias. His velit veniam habemus ne. No doctus neglegentur vituperatoribus est, qui ad ipsum oratio. Ei duo dicant facilisi, qui at harum democritum consetetur. ![valves](https://blog.smartproducts.com/hubfs/valve%20tops.jpg) When comparing a check valve vs. relief valve, it’s easy to assume you’re looking at two completely different valves. In many applications, that isn’t the case. Almost all of our check valves can also function as relief valves. The difference comes down largely to check valve orientation and how pressure is being applied. Here’s how it works and what you should consider when determining which setup is right for your application. ## How Does a Check Valve Work as a Relief Valve? A [check valve](https://blog.smartproducts.com/blog/types-of-check-valves) is designed to open when enough force is applied in the intended flow direction. Fluid or air reaches the valve, pressure overcomes the valve’s opening pressure, and the valve opens. As that pressure diminishes, the check valve begins to close. A pressure relief valve works with the same basic pressure principle, but the application is different. Instead of opening to allow normal system flow, the valve opens when pressure builds to a certain point and needs to be relieved. For many of our valves, changing from one function to the other is a matter of where the valve is installed in the application. ## How Check Valve Orientation Affects Operation A check valve’s installation direction determines which way fluid can flow through it. The valve begins to open when inlet pressure exceeds outlet pressure by a specified amount, called the opening pressure. As that pressure difference decreases, the valve moves toward closing, helping prevent reverse flow. In a pressure-relief arrangement using a valve designed for that purpose, the inlet faces the pressurized system and the outlet leads to a lower-pressure discharge path. When the pressure difference reaches the valve’s opening threshold, fluid flows out to reduce system pressure. Flow still passes through the valve in its intended direction. The key is how the valve is connected within the system and its intended use within the application.   ## Check Valve Opening Pressure in Active and Passive Applications Understanding check valve opening pressure also means understanding where the force acting on the valve comes from. An active application has something creating flow through the system. Consider a pump moving water: Pump starts → water flows → pressure acts on the valve → valve opens As the pressure decreases, the valve begins to close. A passive application works differently. Instead of a pump actively creating flow through the valve, pressure may be building inside a container. Pressure builds → opening pressure is reached → valve begins to open → pressure is relieved This passive condition is what allows a properly oriented check valve to perform the function of a pressure relief valve. ## Different Types of Check Valves Can Serve Different Purposes When comparing different types of check valves, it’s important to consider how the specific valve is designed and whether its orientation can be changed.   Almost all of our products can be used as both check valves and relief valves. Side Seal and Flanged [Models 154 and 191](https://smartproducts.com/check-valves/series-100-miniature-modular-check-pressure-relief-valves/), for example, can be flipped depending on the intended application. There are exceptions. NPT [Models 103 and 109](https://smartproducts.com/check-valves/series-100-miniature-modular-check-pressure-relief-valves/) can’t be flipped in the same way. These valves have a more dedicated purpose, so you’ll need to account for their intended operation when specifying them for an application.  ![](https://blog.smartproducts.com/hs-fs/hubfs/undefined-2.png?width=600&height=300&name=undefined-2.png)  This is why you shouldn’t select a valve based on the terms “check valve” or “relief valve” alone. You also need to consider the specific valve style, orientation and pressure requirements. ## Choosing Between a Check Valve vs. Relief Valve The question isn’t always whether you need one type of valve or the other. It may be whether the same valve can be configured for the function you need. Consider where the pressure is coming from, which direction it’s acting on the valve, and the required opening pressure. For many applications, one valve design can perform either function. For others, a dedicated-purpose valve may be the better or necessary choice. Determining the proper valve, orientation, and opening pressure for your application can be tricky. To make sure you’re sourcing the right check valve or pressure relief valve for your system, contact our team to discuss your application and pressure requirements. [![320 x 100-PNG](https://no-cache.hubspot.com/cta/default/46397732/interactive-213198294437.png)](https://blog.smartproducts.com/hs/cta/wi/redirect?encryptedPayload=AVxigLLUX2WcxFtH2FD6wVfW72pk2%2FAJ40wlk0lITBQuNbL%2Fm19M3WLFL2mAIPj%2BcHVnaki0i8G2BWPbXpKhEJ4U3WvHClN9cmkOUFuN8%2F%2Ft%2BG8aTZp1ibjweMrDwzHLq5WIMsfeCjFXw4I70Vw7P9f3Ek0rB1tHVEp6hBHUqqQe0Hmbk2QPpcSR6%2B9GqiyqTo0I1dapq9Mb1leX8LUNbQ%3D%3D&webInteractiveContentId=213198294437&portalId=46397732) ## Related Posts [![Smart Products](https://smartproducts.com/wp-content/uploads/2024/12/whitelogo-01.png)](https://smartproducts.com/) 644 Fanning Fields Rd. 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