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: 8:00 am to 4:00 pm Phoenix Time
Saturday and Sunday: Closed
- Orders costing more than $300 WILL be required to have signature confirmation upon delivery.
- Handling time is typically only 1 day.
- Any item ordered after 1pm Phoenix time, may not ship same-day.
- Call us if you require expedited shipping and we can give you quotes based on your needs.
Return Policy:
- All products, except as noted below, are eligible for return up to 30 days after receipt of item.
- For returns, an RMA form must be filled out HERE or customers can call for additional help.
- Shipping costs will be deducted from all returned items.
- Any item that is missing accessories, original packaging, or is not returned in the same condition that it was received in, may be subject to a re-stocking fee up to 100% based on the condition we receive it in.
- Items broken, damaged, or inoperable due to installer error will not be refunded.
- Fill out the return form or give us a call to obtain an RMA and return shipping label.
- There are no returns on the Pentair Colorsync 618031
- No returns on pool cleaners.
- No returns on opened seals and o-rings.
- No returns on capacitors.
- If a light is returned because it "doesn't work" and it tests fine, the cost to ship and a re-stocking fee will be deducted from the refund.
- All products denied upon arrival at customers house WILL be charged the cost to ship.
- Visa Gift Card Promotions: Gift cards are sent within 14 days of the order. When accepting the Visa Gift card, you agree that if your order is returned or refunded, this amount will be deducted from the refunded amount. All Visa Gift cards are sent via email in an E-Gift Card format and are non refundable.
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