Rola-Chem Injector Check Valve | 521170
RolaChem
SKU: 521170
Rola-Chem 521170 Injection Check Valve – 3/8" Hose Barb x 1/4" MNPT (PVC) – For Chemical Feed Lines
The Rola-Chem 521170 is a durable injection check valve used on pool/spa chemical feed systems to help ensure one-way flow into the plumbing line. It helps prevent pool water from backing up into the chemical feed tubing and supports more consistent, leak-resistant chemical dosing at the injection point.
Key Features
- Part Number: 521170
- Type: Injection check valve (one-way)
- Body Material: PVC
- Inlet Connection: 3/8" hose barb (for chemical tubing)
- Outlet Connection: 1/4" MNPT (male NPT) for threading into an injection fitting/port
- Purpose: Helps prevent backflow and supports reliable chemical feed at the injection point
Common Applications
- Chemical injection point on pool/spa return plumbing
- Peristaltic metering pump installations using 3/8" feed tubing and a 1/4" NPT injection port
- Replacing a worn, leaking, or stuck injection/check valve in an existing dosing setup
Compatibility Notes
- Designed for systems that use 3/8" chemical tubing on the feed side and a 1/4" NPT threaded injection point.
- If your tubing size or injection port size is different, choose the correct barb/NPT combination before ordering.
- Install at the injection point in the correct flow direction (arrow/flow marking if present).
Installation Notes
- Threaded connection (1/4" MNPT): Use PTFE thread tape or a non-hardening thread sealant compatible with PVC. Tighten snug—do not over-tighten.
- Tubing connection (3/8" barb): Push tubing fully onto the barb. Use a clamp if your application requires it.
- Orientation: Install so chemical flows toward the injection point; reversing it can block flow or allow backflow.
- Location: Injection points are typically placed downstream of equipment (and after heaters when applicable) following your chemical system’s guidelines.
Signs It’s Time to Replace
- Chemical line drains backward or loses prime
- Water backs up into the feed tubing or pump line
- Visible leaking at the injection point or around the valve body
- Inconsistent chemical delivery even after confirming pump operation
Related Products
- Rola-Chem Injectors & Injection Fittings
- Chemical Injection Check Valves
- 3/8" Chemical Tubing
- 1/4" NPT Injection Fittings
- PTFE Thread Tape
- Thread Sealant for Plastic Threads
Installation & Maintenance Tips
- Flush/relieve pressure before removing the valve, and avoid tightening threaded plastic parts under pressure.
- Keep the injection point clean—scale or debris can prevent the check valve from sealing properly.
- If you service the system seasonally, inspect tubing ends for swelling/cracking and trim back to fresh tubing before reattaching.
- When reinstalling, use only enough thread sealant to seal—excess tape/sealant can interfere with seating or crack plastic threads if over-tightened.
- After startup, verify there is no seepage at the threads and that the feed line holds prime between dosing cycles.
Questions about returns? View our return policy.
Hours Of Operation:
Monday - Friday: 7:00 am to 5:00 pm Phoenix Time
Saturday: 8:00 am to 2:00 pm
Sunday: Closed
- We do not ship on Saturday or Sunday.
- Orders totaling more than $300 will require signature confirmation upon delivery.
- We process and prepare orders for shipment within 1 business day. Please note that many other pool supply retailers require 3–5 days of handling time before shipping.
- Orders placed after 1:00 pm Phoenix Time may not be eligible for same-day shipment.
- Expedited shipping options are available at checkout.
Return Policy:
- Products that are received damaged will receive a refund in store credit.
- Most products are eligible for return within 30 days of receipt, except where noted below.
- To initiate a return, please complete an RMA form prior to sending your item back.
- Original shipping costs are non-refundable and will be deducted from the return credit.
- Items returned missing accessories or original packaging, or that are not in the same condition as received, may be subject to a restocking fee of up to 100% depending on the condition of the item upon return.
- Some returns will be charged an automatic 15% restocking fee.
- We are unable to issue refunds for items that have been damaged or rendered inoperable due to installer error.
- Please complete the return form to receive your RMA number and return shipping label.
- Chemical products are not eligible for return under any circumstances.
- The Pentair Colorsync 618031 is not eligible for return.
- Pool cleaners are not eligible for return.
- Opened seals and o-rings are not eligible for return.
- Capacitors are not eligible for return.
- Plastic popup tools are not eligible for return.
- Automation components and circuit boards are not eligible for return.
- If a light is returned due to a reported malfunction and is found to be fully operational upon testing, return shipping costs and a restocking fee will be deducted from the refund.
- Orders refused at the time of delivery will be subject to the original shipping costs being deducted from the refund.
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