The acid neutralization trap contains a large alkaline (calcium hydroxide) element cartridge to neutralize hydrous acids before they enter the vacuum pump. The element changes from white to bluish-transparent when spent and can be observed through the transparent trap body. For high vapor loads, place a cold trap between acid neutralization trap and pump to avoid rapidly saturating element. For pumps with free air displacement less than 100 liters per minute, use trap 1420H-21. For pumps with free air displacement between 101 and 500 liters per minute, use trap 1420H-20. Use replacement element 1420E-01. Also available in pump connection kit 1402K-25. Kit 1402K-25 includes KF 25 elbow, hinge clamp and centering ring.