---
kind: "section"
citation: "21 C.F.R. § 177.2250"
title: "21"
number: "177.2250"
heading: "Filters, microporous polymeric."
url: "https://uscodex.org/cfr/21/177.2250"
---

# §177.2250. Filters, microporous polymeric.


Microporous polymeric filters identified in [paragraph (a)](#a) of this section may be safely used, subject to the provisions of this section, to remove particles of insoluble matter in producing, manufacturing, processing, and preparing bulk quantities of liquid food.

- (a) Microporous polymeric filters consist of a suitably permeable, continuous, polymeric matrix of polyvinyl chloride, vinyl chloride-propylene, or vinyl chloride-vinyl acetate, in which finely divided silicon dioxide is embedded. Cyclohexanone may be used as a solvent in the production of the filters.
- (b) Any substance employed in the production of microporous polymeric filters that is the subject of a regulation in parts [170](/cfr/21/part170.md) through [189](/cfr/21/part189.md) of this chapter must conform with any specification in such regulation.
- (c) Cyclohexanone when used as a solvent in the production of the filters shall not exceed 0.35 percent by weight of the microporous polymeric filters.
- (d) The microporous polymeric filters may be colored with colorants used in accordance with [§ 178.3297](/cfr/21/178.3297.md) of this chapter.
- (e) The temperature of food being processed through the microporous polymeric filters shall not exceed 180 °F.
- (f) The microporous polymeric filters shall be maintained in a sanitary manner in accordance with good manufacturing practice so as to prevent potential microbial adulteration of the food.
- (g) To assure safe use of the microporous polymeric filters, the label or labeling shall include adequate directions for a pre-use treatment, consisting of washing with a minimum of 2 gallons of potable water at a temperature of 180 °F for each square foot of filter, prior to the filter's first use in contact with food.

## Notes

### Amendments

[42 FR 14572, Mar. 15, 1977, as amended at 56 FR 42933, Aug. 30, 1991]

### Authority

Authority: 21 U.S.C. 321, 342, 348, 379e.

### Source

Source: 42 FR 14572, Mar. 15, 1977, unless otherwise noted.

### Amendments

[42 FR 14572, Mar. 15, 1977, as amended at 56 FR 42933, Aug. 30, 1991]