| Share | Phrase |
|---|
| 22.00% | prevent backflow [perform operation] |
| 19.24% | backflow zone |
| 9.56% | backflow bubble |
| 8.90% | backflow restrictor |
| 6.36% | fuel backflow |
| 4.96% | backflow fitting |
| 4.28% | gas backflow |
| 3.20% | fluid backflow |
| 2.83% | restrict backflow [perform operation] |
| 2.60% | block backflow [perform operation] |
| 2.25% | backflow form |
| 2.10% | backflow valve |
| 1.92% | backflow port |
| 1.91% | backflow conduit |
| 1.48% | current [chronology] backflow |
| 1.36% | avoid backflow [perform operation] |
| 1.33% | water backflow |
| 1.08% | air backflow |
| 0.93% | allow backflow [perform operation] |
| 0.85% | backflow means |
| 0.75% | cause backflow [perform operation] |