Hold Downs

BED LIMITERS & HOLDDOWNS

 There are many variations and purposes for bed limiters and holddown devices. As the names imply, their general purpose is to hold packing, random or structured, in place within the process column. However, in some cases, holddowns are used as a platform to support and level a liquid distributor.

• For random packing, the bed limiters consist of expanded metal attached to a flat bar framework that is clamped to a support ring.
• For structured packing, depending on the column diameter, the holddown involves a much-reduced framework, which adequately covers all the structured packing bricks.

Both devices can be mechanical designed to withstand specified up-lift requirements.

Random Packing Bed Limiter (RBL-100)

Structured Packing Bed Limiter (SBL-100)

The most cost-effective bed limiter for random packing is the holddown device which is made an integral part of the Orifice/Riser liquid distributor.  Expanded metal or anti-migration bars are welded beneath the vapor risers to prevent movement of the random packing during normal operation and upset conditions.  Integral bed limiters have the following beneficial features:

1. They eliminate the cost of a separate hold down
2. They eliminate the cost for an additional support ring
3. The integral bed limiter never interferes with the liquid distribution
4. There are additional cost savings in the elimination of installation costs for tower attachments and the bed limiter